OphthalmologyTimes - Cataract Surgery Resource Center

History

A 65-year-old male with long-standing ocular surface disease presents for evaluation of decreased vision and pain of the left eye for one week. The patient has an extensive ocular history, including congenital cataracts, bilateral cataract extraction and later secondary placement of anterior chamber intraocular lenses, then subsequent development of bilateral glaucoma and cicatricial conjunctivitis resulting in bilateral limbal stem cell deficiency (LSCD), recurrent epithelial defects, dry eye disease, fornix foreshortening, trichiasis, and entropion. His glaucoma has been managed at an outside facility with maximum topical medical therapy for many years. His bilateral upper eyelid entropion was repaired with oral mucous membrane graft approximately one year prior to presentation. He wears bandage contact lenses and has been using moxifloxicin hydrochloride ophthalmic solution 0.5% (Vigamox®, Alcon, Fort Worth, TX) twice a day and loteprednol etabonate ophthalmic suspension 0.5% (Lotemax®, Bausch+Lomb, Bridgewater, NJ) four times a day in both eyes for at least two years for his severe ocular surface disease. Most recently, he has had to switch from moxifloxicin to polymyxin B sulfate trimethoprim due to a change in his insurance coverage. He was seen by his outside ophthalmologist and referred to the emergency department given concern for severe dry eye disease complicated by a corneal ulcer in the left eye.

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Examination

On initial evaluation, the patient had a best-corrected visual acuity of 20/70 with pinhole vision of 20/60 in the right eye, and counting fingers in the left eye. Intraocular pressures (IOP) were 14 bilaterally. External examination showed extensive chronic inflammatory changes of the eyelids bilaterally, including severe induration, thickening, and notching of the eyelid margins, meibomian gland dysfunction and trichiasis. He had diffuse conjunctival injection, greater in the left eye, with forniceal foreshortening in both eyes. The cornea in the right eye had neovascularization 3-mm onto the cornea superiorly, diffuse faint subepithelial haze, and a whorling pattern of the epithelium with scattered punctate epithelial defects. The cornea in the left eye showed a central epithelial defect with associated infiltrate consistent with a corneal ulcer as well as superior fibrovascular pannus 3-mm onto the cornea and band keratopathy temporally. The anterior chamber in the left eye had a hypopyon and there were bilateral anterior chamber intraocular lenses. There was a poor view to the posterior pole in both eyes due to the severe ocular surface disease, but B-scan ultrasound was normal bilaterally.

Discussion and diagnosis

Given the patient’s history of recurrent and non-healing epithelial defects from LSCD, he was at higher risk of developing a corneal ulcer. His long-term contact lens use with chronic administration of loteprednol etabonate ophthalmic suspension 0.5% and moxifloxicin hydrochloride ophthalmic solution 0.5% made a fungal infection in the left eye high on the differential. A culture was obtained and the patient was started on fortified antibiotics (vancomycin 25mg/ml and tobramycin 14mg/ml) and natamycin ophthalmic solution one drop every 2 hours. The following day natamycin was increased to one drop every hour and oral voriconazole was also added due to concern of possible worsening. Corneal cultures were positive for rare coagulase negative staphylococci without fungal elements. Heidelberg Retina Tomograph II-Rostock Cornea Module (Heidelberg Engineering, Carlsbad, CA) was negative for filamentous fungi, but was positive for yeast. Since suspicion for fungal infection was high, the patient was monitored very closely over the next several months and maintained on a regimen of antibiotic, antiviral and antifungal medications until the corneal infection resolved.

An even more challenging aspect of this patient’s care is the long-term management of his complex combination of ocular diseases. Given the extended use of topical glaucoma medications, the patient’s cicatricial conjunctivitis was thought to be due to medicamentosa,^1-5 also known as pseudopemphigoid. However, our patient denied ever having a conjunctival biopsy to rule out mucous membrane pemphigoid (MMP). The patient was then referred to a uveitis specialist who expressed concern for worsening ocular surface inflammation with a conjunctival biopsy. He was also not a candidate for systemic immunomodulatory therapy (even if a biopsy were positive for MMP) due to his presumed infectious keratitis and history of thrombocytopenia of unclear etiology.

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The three principal aims in the treatment of cicatricial conjunctivitis include managing the ocular surface and dry eye disease, eliminating or minimizing treatment toxicity, and suppressing inflammation.^{2, 6} The ocular surface disease is a result of the inflammation of the conjunctiva and eyelids. Blepharitis, trichiasis, entropion, dry eye, limbal stem cell deficiency, persistent epithelial defects, and microbial keratitis can all result from inflammation, poor lid closure or lid malposition, trichiasis and poor tear film.⁶ Our patient unfortunately suffered from all of these. He was started on oral minocycline for its beneficial anti-inflammatory effects for both the ocular surface and lid inflammation. He was referred to the oculoplastics service for evaluation of his entropion and trichiasis. He was maintained for two years with bandage contact lenses for his recurrent epithelial defects, but the left one was discontinued during the active infection. Amniotic membrane and PROKERA® (Bio-Tissue®, Doral, FL) were also considered for his epithelial defects. Limbal stem cell transplant can be helpful in LSCD, but an autograft was not possible in our patient due to bilateral severe disease and an allograft would require long-term immune suppression, for which he was not a potential candidate. A therapeutic penetrating keratoplasty was also considered, but there was concern for failure of re-epithelialization in the setting of LSCD. Type II keratoprosthesis has also been discussed.

Dry eye management is a vital component of the treatment plan and can often be addressed in a step-wise approach.⁷ Conservative methods including wrap-around glasses and humidified environments should be implemented. Punctal occlusion often occurs spontaneously in this disease due to chronic inflammation, but can be initiated for conservation of tears.^{2, 6} Pharmaceutical tear substitutes are often needed for symptom relief, but especially in cases of drug-induced pseudopemphigoid, use of preservative-free artificial tears is paramount.^{2, 6}Autologous serum tears can also be used.⁸ Gas-permeable corneal or scleral lenses may also improve surface hydration and vision in some patients.⁹ Our patient was encouraged to use preservative-free artificial tears when needed and used gas-permeable contact lenses. He was also referred for Boston Sight® PROSE treatment (Boston Foundation for Sight, Needham, MA).

Eliminating treatment toxicity

Eliminating or minimizing treatment toxicity is especially important in cases of medicamentosa-related pseudopemphigoid as well as in all cases of moderate to severe dry eye disease. One of the principal culprits of ocular toxicity is the preservative benzalkonium chloride, which is a component of many glaucoma medications and most re-usable eye drop preparations.^1-3 Topical medications with preservatives can overtime induce chronic corneal epitheliopathy and also LCSD. Therefore, all patients with pseudopemphigoid or moderate to severe dry eye should be treated with preservative-free anti-glaucoma medications. Our patient was referred to the glaucoma service and immediately transitioned to all preservative-free glaucoma drops, but he had already been treated with topical glaucoma medications with preservatives for many years prior.

Suppressing inflammation is also essential in the prevention of ocular surface disease progression.⁶ Less potent topical steroid drops or “soft” steroids, such as loteprednol, are good options for long-term management of ocular surface disease since they provide the therapeutic benefit with less risk of IOP elevation.(7) Non-preserved topical steroids, such as methylprednisolone 1% can also be formulated and systemic immunomodulation may be necessary in severe disease. Our patient was not a candidate for systemic immunosuppression due to his active infection and other systemic diseases. He had previously been maintained on loteprednol etabonate ophthalmic suspension 0.5% and continued on this in the right eye. Due to his extensive history of glaucoma, close glaucoma follow up was necessary for IOP monitoring.

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The patient currently has a visual acuity of 20/70 with pinhole vision of 20/60 on the right and light perception on the left due to progressive corneal opacification with healing of the corneal ulcer. He is currently using Air Optix® Night and Day® Aqua (Alcon, Fort Worth, TX) contact lenses bilaterally. He is using preservative-free glaucoma drops and artificial tears as well as moxifloxicin hydrochloride ophthalmic solution 0.5% twice a day in both eyes. He continues to use loteprednol etabonate ophthalmic suspension 0.5% only in the right eye once a day. There is still discussion of a possible therapeutic penetrating keratoplasty versus keratoprosthesis for the left eye in the future.

Conclusion

Drug-induced pseudopemphigoid is a complicated condition with many ocular manifestations, including dry eye disease and cicatricial conjunctivitis. Its treatment requires a multidisciplinary approach, including cornea, oculoplastic, glaucoma and uveitis specialists, and patients often need a combination of several available treatments for disease control. Close monitoring is necessary to prevent the development of corneal infections or other devastating ocular effects.

References

Iovieno A, Cimino L, Fontana L. Unilateral ocular pseudopemphigoid in a patient with glaucoma. JAMA ophthalmology. 2015;133(2):e143483.
Fiore PM, Jacobs IH, Goldberg DB. Drug-induced pemphigoid. A spectrum of diseases. Arch Ophthalmol. 1987;105(12):1660-3.
Gibran SK. Unilateral drug-induced ocular pseudopemphigoid. Eye (Lond). 2004;18(12):1270.
Patten JT, Cavanagh HD, Allansmith MR. Induced ocular pseudopemphigoid. Am J Ophthalmol. 1976;82(2):272-6.
Wilson FM, 2nd. Adverse external ocular effects of topical ophthalmic medications. Surv Ophthalmol. 1979;24(2):57-88.
Dart J. Cicatricial pemphigoid and dry eye. Semin Ophthalmol. 2005;20(2):95-100.
Stevenson W, Chauhan SK, Dana R. Dry eye disease: an immune-mediated ocular surface disorder. Arch Ophthalmol. 2012;130(1):90-100.
Poon AC, Geerling G, Dart JK, Fraenkel GE, Daniels JT. Autologous serum eyedrops for dry eyes and epithelial defects: clinical and in vitro toxicity studies. Br J Ophthalmol. 2001;85(10):1188-97.
Tan DT, Pullum KW, Buckley RJ. Medical applications of scleral contact lenses: 2. Gas-permeable scleral contact lenses. Cornea. 1995;14(2):130-7.

Seanna Grob, MD, MAS

E: Seanna_Grob@meei.harvard.edu

Take-home: Five years of experience with the Rayner T-flex aspheric IOL show it to be a safe, highly effective long-term method of correcting the widest possible range of sphere and cylinder errors in pseudophakic patients with pre-existing corneal astigmatism.

There have been numerous studies of the short-term results (up to 1 year) with toric IOLs, with a general consensus that they are an effective tool for managing astigmatism in cataract-surgery patients. But what about performance over the longer term – say, past 5 years?

To answer this question, we conducted a retrospective analysis including 507 eyes of 417 patients presenting for cataract surgery over a 5-year period (from August 2007 to August 2012). This was a single-surgeon, single-centre study utilising the T-flex IOL (Rayner Intraocular Lenses, Hove, UK). We included all comers: patients with primary and secondary astigmatism, post-refractive surgery, penetrating keratoplasty, keratoconus and corneal scarring. However, to be eligible for inclusion, patients had to have a corneal astigmatism of +0.7 D or greater at the corneal plane (approximately +1.0 D at the IOL plane).

A single surgical technique was used throughout the study. After administering a topical anaesthetic, with the patient seated upright, I first marked the cardinal axis to avoid cyclo-torsion. Then, when the patient was in a supine position, I marked the steep axis with

which the toric IOL is aligned. Finally, I marked the capsulorhexis. This is because a well-centred capsulorhexis is very important to ensure a uniform 360° overlap that will maximise the rotational stability of the lens and provide consistent effective lens position. I performed bimanual surgery with vertical phaco chop to remove the nucleus and then implanted the lens using a Rayner soft-tipped injector through a clear corneal incision that was initially 2.8 mm but later 2.4 mm. The lens was placed in the capsular bag then the viscoelastic was removed from behind the lens.

Analysis

Analysis of sphere correction

An analysis of sphere correction showed that, preoperatively, the sphere ranged from –10.5 to +9.0 D and axial length from 20.99 to 27.75 mm. However, the postoperative mean absolute error was 0.35 D and the standard deviation was 0.46 D (Figure 1). With regards to cylinder correction, preoperative refractive astigmatism ranged from 0.0 to 7.25 D and keratometric astigmatism from 0.67 to 7.86 D. Additionally, keratometric values ranged from 33.35 to 59.00 D and IOL toricity from 1.0 to 11.0 D. Postoperatively, mean cylinder was 0.26 D with a standard deviation of 0.35 D, and 90% of patients had 0.5 D or less of astigmatism. Stratifying the results according to with-the-rule and against-the-rule astigmatism revealed that with-the-rule cases generally did better than those patients with against-the-rule astigmatism.

Overall, 23 patients had 1.0 D, seven patients had more than 1.0 D and no patient had more than 2.0 D of residual astigmatism. Interestingly, the seven patients with more than 1.0 D of residual astigmatism all had primary astigmatism. However, they all had less astigmatism postoperatively, indicating that in a small percentage of patients there are factors other than anterior corneal curvature contributing to total ocular astigmatism.

Very few complications were noted in this 507-eye study. Specifically, two patients had radial tears in the continuous curvilinear capsulorhexis, but we were still able to implant the T-flex in the capsular bag without any problems. The rate of cystoid macular oedema was 1%; all cases were resolved with topical steroids and ketorolac treatment. There were no patient returns to theatre to re-rotate misaligned lenses.

Tips and considerations

It has been established that biometry is the cornerstone of good outcomes following implantation of a toric IOL. Indeed, the single biggest source of error in refractive outcomes following toric lens implantation is inaccurate biometry. When a cataract patient presents at my centre, keratometry is one of the first tests I perform. However, it is important to remember that keratometry measures reflection from the tear film and not the curvature of the cornea. If a surgeon overlooks this simple but vital point, their patients’ refractive outcomes will likely be doomed from the outset. Although Rayner helpfully provides the Raytrace system, a quick and easy to use online IOL power calculator, I prefer Dr Jack Holladay’s program. This is because it allows me to import data electronically from the IOL Master (Carl Zeiss Meditec) that I use for keratometry (both calculating the axis of astigmatism and the power of correction required), thus eliminating the possibility of transcription errors.

Another important point is to ensure the A-constant values are continually optimised – in my case, the A-constant was optimised/personalised at 118.7. Dr Holladay’s program also provides a chart that gives the degree of toricity recommended for any given spherical power.

A final issue worth addressing here is a fear experienced by many cataract and refractive surgeons – that of IOL misalignment. Reassuringly, however, a paper published by Noel Alpins in the Journal of Cataract and Refractive Surgery in 1997 demonstrated that only about 5% of toric power is lost with a misaligned lens as long as the lens placement is within 10 degrees of intended axis.⁵

Overall, findings from our 5-year “audit” of the Rayner T-flex aspheric lens show that it is a safe, highly effective long-term method of correcting the widest possible range of sphere and cylinder errors in pseudophakic patients with pre-existing corneal astigmatism.

The T-flex solution

The T-flex solution

There are a number of toric IOL options, with variations in material type, design, diameter, incision size and spherical /cylindrical power. In my practice, I regularly use the T-flex aspheric IOL (Rayner Intraocular Lenses Limited, Hove, UK), which offers a precise superior alternative to incisional methods for the treatment of pre-existing corneal astigmatism.³Available in cylinders 1.0 to 11.0 D, and from –10 to +35.0 D for spheres (subject to spherical equivalent), the T-flex IOLs offer a far greater range of cylinder and sphere combinations than most other toric IOLs, thus allowing the correction of significant levels of astigmatism. Typically, once we cross the +1.5 D threshold, many other toric lenses on the market are available in 0.75 D or 1.0 D steps for toricity. The Rayner lens is special because it comes in 0.50 D steps, therefore giving us much more flexibility in treating our astigmatic patients. Additionally, the T-flex incorporates Anti-Vaulting Haptic Technology, which progressively takes up forces generated within the contracting capsular bag, thus maintaining excellent centrational and rotational stability.⁴

Daniel A. Black, MBBS (Qld) FRANZCO FRACS A/FACAsM

E: daniel.black@suneye.com.au

Daniel A. Black is an ophthalmologist in practice at the Sunshine Eye Clinic in Birtinya, Queensland, and a Senior Lecturer at the University of Queensland, Australia. Dr Black states that he has no financial interests in Rayner Intraocular Lenses Ltd.

References

1. Visser N, Bauer NJ and Nuijts RM. J. Cataract. Refract. Surg. 2013; 39: 624-637.

2. Saragoussi JJ. J. Fr. Ophtalmol. 2012; 35(7): 539-545.

3. Rayner. http://www.rayner.com/t-flex. Last accessed 1 September 2014.

4. Claoué C. Clin. Surg. Ophthalmol. 2008; 26(6): 198-200.

5. Alpins NA. Cataract Refract. Surg. 1997; 23(10): 1503-1514.

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Take-home: MIGS is a viable option in patients with mild–moderate glaucoma with an IOP that has been unable to be controlled by medications or who have poor medication compliance. The combination of MICS and MIGS can offer an effective surgical treatment for POAG when the IOP reduction following cataract surgery alone is not sufficient to reduce the need for glaucoma therapies.

Reviewed by Christophe Baudouin, MD, PhD, FARVO

More than 60.5 million people worldwide were affected by glaucoma by the year 2010; this is expected to increase to nearly 80 million by 2020.¹ Of these patients, 74% will have primary open-angle glaucoma (POAG), the number two cause of blindness worldwide. Cataract is the leading cause of blindness. It has been shown that the volumetric growth of cataract can be a risk for high ocular pressure and POAG.

Increasing life expectancy and the high visual requirements of patients have inspired physicians to find new therapeutic strategies to fight these two important causes of blindness. For this reason, new minimally invasive surgery techniques to remove cataract and reduce IOP– microincision cataract surgery (MICS) and micro-invasive glaucoma surgery (MIGS) – have been developed. The two procedures can be performed together.

MICS is an approach to cataract surgery that uses an incision of less than 2.0 mm to reduce surgical invasiveness and at the same time improve surgical outcomes. This technique is the best to perform in eyes with other diseases, such as POAG, because of the low rate of surgical manipulation and induced inflammations.

While there had previously been limited surgical options for patients with mild–moderate glaucoma, MIGS procedures are creating new options for patients who do not meet the criteria for trabeculectomy. These procedures have a better safety profile than other invasive techniques, with fewer complications and a more rapid recovery time. They have been shown to be effective in decreasing IOP as well as a patient’s need for medications, which is important given a typically low compliance rate for medication adherence.²

The main indications for MIGS are POAG with mild–moderate optic nerve damage, pseudoexfoliation glaucoma or pigmentary dispersion glaucoma, POAG uncontrolled with maximum pharmacologic treatment or with barriers preventing adequate medication dosing.

The main contraindications are angle-closure glaucoma, secondary glaucoma, moderate–advanced POAG, previous unsuccessful glaucoma surgery or severely uncontrolled IOP.³

There are several definitions of MIGS, but the American Glaucoma Society, which is the largest society of glaucoma specialists in the United States, provides the following working definition:

· IOP lowered by improving the outflow of eye fluid. This is the same mechanism that is used in traditional glaucoma surgery.

· Approach from inside the eye.

· Limited surgical manipulation of the sclera.

· Little manipulation of the conjunctiva.

In meeting these criteria, MIGS procedures do not preclude the possibility of future, more traditional surgical approaches such as trabeculectomy or tube shunt surgery.

Overall, MIGS procedures have been touted as safer than traditional trabeculectomy or tube shunt surgeries. This is because they do not have some of the associated complications of the traditional procedures, such as low eye pressure (hypotony) and bleb infection.

Many MIGS procedures involve the implantation of small devices. MIGS procedures are generally faster than trabeculectomy and tube shunt surgeries, and shortened surgical time can be very important for the safety of the patient. Many MIGS procedures are combined with cataract surgery, adding a short amount of time to the total surgical procedure.

Lastly, an important point is that while most MIGS procedures are safe, they are less effective than other traditional surgical procedures in lowering eye pressure, for example in patients affected by severe glaucoma with IOP greater than 30 mmHg.

MIGS with microstents can provide an effective way to treat glaucoma in a less invasive manner and earlier in the disease process. Although good surgical skills and experience are required, recovery is faster and there are fewer complications compared with traditional procedures, as tissue dissection is not required.

MIGS with microstents

Over recent years, new microstent devices for ab interno MIGS have been developed.

Aimed at the subconjunctival space is the XEN Gel Stent (AqueSys). Other implants – including the Hydrus Microstent (Ivantis) and the first- and second-generation iStent Trabecular Micro-Bypass Stents (Glaukos) – target the Schlemm canal, while the third-generation iStent and the CyPass microstent (Transcend Medical) are aimed at the suprachoroidal space.

Personal experience

Figure 1Of the devices listed above, the microstents with which we have the most experience are the iStent Trabecular Micro-Bypass Stent (Glaukos, Laguna Hills, CA) (Figure 1) and the XEN Gel Stent (Aquesys Inc.) (Figure 2).Figure 2

The iStent Trabecular Micro-Bypass Stent received FDA approval in 2012. This is the smallest FDA-approved device, measuring 0.3 mm in height and 1 mm in length, and is a heparin-coated non-ferromagnetic titanium stent with a snorkel shape to facilitate implantation. The device is placed using a sterile single-use inserter through a 1.5 mm corneal incision. The applicator is inserted into the anterior chamber and across the nasal angle, while the angle is carefully visualised with a goniolens. The pointed tip allows penetration of the trabecular meshwork and insertion into Schlemm’s canal, and three retention arches ensure that the device will be held in place. In our department, 23 eyes were implanted with this device. iStent implantation with phacoemulsification resulted in a significantly lower long-term decrease in IOP and the number of medications used compared with phacoemulsification alone. No major complications were found in our series.

The XEN Gel Stent has a CE mark and is an investigational device that is currently undergoing clinical trials. The implant is made of a soft collagen-derived gelatin that is known to be non-inflammatory. The XEN Gel Stent is 6 mm long and about the width of a human hair. The goal of implantation is to create an outflow path of aqueous humour from the anterior chamber into the non-dissected tissue of the subconjunctival space. A little bleb is obtained by injecting mitomycin-C in the superotemporal sub-conjunctival space, which is then massaged with a sponge towards the superonasal quadrant. The implant is injected through a small corneal incision into the superonasal quadrant, passing through the Schlemm canal with an inserter similar to those used for IOLs. The device is easily seen through the conjunctiva.Figure 3

Like other implants, it can be inserted in conjunction with MICS. We have good experience (21 implants) of this combined surgery with 1 year of follow up. IOP was reduced from 25.8 mmHg ± 5.26 mmHg (mean ± standard deviation) at baseline before surgery to 13.8 ± 1.09 mmHg at 1 year for the combined surgery with XEN Gel stent. Furthermore, the mean number of glaucoma medications was reduced from 2.6 at baseline before surgery to 0 at 1 year. The reduction of IOP has persisted and we have experienced no major complications. There was just one patient, who had not interrupted antiplatelet therapy although preoperative discontinuation was required, in whom we did not succeed in implanting the device because of a diffuse sub-conjunctival haemorrhage soon after mitomycin-C injection.Figure 4

After implanting this device, one of the most interesting features of follow-up is the possibility of verifying the correct position of the stent by using an anterior optical coherence tomography (OCT). Recently, we tested a combined anterior and posterior swept source OCT, the DRI OCT Triton plus (Topcon Medical Japan Co., Ltd.), which provides deep images of the anterior chamber and a better penetration of the deeper layers of the eye such as the sclera. As shown in Figures 3–5, the bleb and the XEN Gel stent conforming to tissue in a human eye are easily detected with this new OCT. These follow-up images allow measurements and detection of any postoperative complications such as tiny dislocations of the Figure 5device.

Conclusions

In patients with mild–moderate glaucoma with an IOP that has been unable to be controlled by medications or who have poor medication compliance, MIGS appears to be a viable option. Clinical trials have shown there to be a significant decrease in IOP over periods of up to 24 months, along with a significant decrease in medication usage. The procedure has maintained a high safety profile with minimal adverse effects. There are a few FDA-approved devices, such as iStent, and multiple new devices pending, such as XEN Gel Stent. MIGS can provide a method of treatment for glaucoma patients that decreases reliance on medications without the safety risks of more invasive procedures.

The combination of MICS and MIGS by implanting a microstent can offer an effective surgical treatment of POAG because the reduction of IOP caused by cataract surgery alone may not be sufficient to reduce a patient’s need for glaucoma therapies.

References

1. Quigley HA, Broman AT. Br. J. Ophthalmol. 2006; 90(3): 262-267.

2. Randy Craven E, et al., J. Cataract. Refract. Surg. 2012; 38(8): 1339-1345.

3. Francis BA, et al., Ophthalmology 2011; 118: 1466-1480.

Dr. Antonio Toso

E: antonio.toso@gmail.com

Dr. Simonetta Morselli

E: simonetta.morselli@gmail.com

Dr. Alessandra De Gregorio

E: adegregorio@email.it

Dr. Alberto Amisano

E: amisano.alberto@gmail.com

Dr. Toso is head of the Vitreoretinal Surgery Unit, Department of Ophthalmology, S. Bassiano Hospital, Bassano del Grappa, Italy.

Dr. Morselli is head of the Department of Ophthalmology at S. Bassiano Hospital, where Dr. De Gregorio is a consultant and Dr. Amisano practices.

None of the authors have financial interests in the products mentioned.

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Severe myopia affected the attitudes of both Theodore Roosevelt and Ronald Reagan, but in opposite ways, according to biographer Edmund Morris.

“Since both of them became aware of their myopia in their early teens, it was obviously a formative experience for both of them,” Morris told Ophthalmology Times.

Discovering that his vision could be corrected gave Roosevelt an appreciation for fine details, and he developed a talent for remembering faces, Morris said. Reagan, on the other hand, seemed content to view the world in broad generalities, he said.

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Morris, who has written books about both U.S. presidents, contrasted the effects of myopia on them in the Michael F. Marmor, MD, Lecture in Ophthalmology and the Arts at the 2015 American Academy of Ophthalmology meeting.

Theodore Roosevelt discovered his myopia at age 13 after getting his first gun and noticing his friends were shooting at targets he could not see. He mentioned the problem to his father and soon received his first pair of glasses.

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“I had no idea how beautiful the world was until I got those spectacles,” Roosevelt wrote in his autobiography.

The experience gave him sympathy for efforts in public schools to assist children with all kinds of physical disabilities.

Clear vision became so important to Roosevelt that he later carried multiple pairs of spectacles with him. The pince-nez became a trademark for him.

Roosevelt (cont.)

For a 2011 article in the Theodore Roosevelt Association Journal, Milton Bruce Shields, MD, a professor in the Department of Ophthalmology and Visual Science at the Yale University School of Medicine, searched for a pair of the glasses in collections devoted to Roosevelt. He could not find any.

However, according to a report of a pair examined at the Massachusetts Eye & Ear Infirmary in 1959, they measured -7 D.

Later, Roosevelt lost vision in his left eye because of a cataract and possibly because of a retinal detachment resulting from a boxing match while he was president, Dr. Shields wrote.

Growing up with poor vision may explain Roosevelt’s highly sensitive hearing. His writing is filled with auditory memories, Morris said.

Roosevelt also developed a keen intellectual appetite, devouring a book a day. His photographic memory impressed many of the people he met during his world travels. “Which of our elected presidents of the last century have showed a comparable knowledge of and sensitivity toward foreign cultures?” Morris asked.

And Roosevelt could often identify people he had met only briefly many years before.

Reagan was a different story

By contrast, “Ronald Reagan thought the world around him was a blur, and not a particularly interesting one, because he was born in rural Tampico, North Illinois,” with its featureless topography, Morris said. “Much of his certainty [and] lack of interest in peripheral detail derived from the simple geometry that encircled him in his formative years.”

He discovered his myopia as a teenager when he tried on his mother’s spectacles, and in his words, “discovered the gloriously sharply outlined world.” His visual acuity was later measured at 20/200.

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Myopia influenced Reagan’s choice of swimming and football as sports because they required less distance vision, Morris said. It also limited him to a desk job during World War II.

Yet in contrast to Roosevelt, Reagan often chose not to correct his myopia out of concern for his personal appearance.

When he first went to Hollywood, a girlfriend advised him, “If you could just take off those glasses, I could get you a screen test.”

His acting career took off. And although he was fitted with a pair of scleral contact lenses, he would not wear them while performing because they gave him a “bug-eyed” look.

He seemed to turn his poor vision to his advantage, Morris said. “Any actor will tell you that it’s a fatal mistake to focus on any particular face in the audience in front of you.”

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At times, he even had difficulty recognizing his own children, Morris said. “His daughter Patti told me that on several instances when she walked in he would look at her with an expression that made it clear that he wasn’t sure whether it was her or his other daughter Maureen.”

When giving political speeches later in his life, he would wear a contact lens in only one eye so that he observed the audience’s reaction with that eye while reading notes with the other, Morris said.

“If I were asked which man most influenced the course of history, the one who embraced the world in all its diversity, or the one who saw it in large blocks of essentials, I guess I would have to answer the guy who couldn’t tell his own children apart,” Morris concluded.

Unexpected head movement can lead to suction loss and displaced laser beam delivery despite safety mechanisms of the femto platform, allowing the femto-laser grid pattern to be delivered into the cornea. (Video courtesy of Sonia Yoo, MD)

Femtosecond laser-assisted cataract surgery (FLACS) is a latest advance in technology that is transforming traditional cataract surgery into a refractive procedure. Multiple studies have shown that laser-assisted cataract surgery can increase precision and reproducibility of the anterior capsulotomy, reduce effective phacoemulsion time, cause less postoperative inflammation to the anterior chamber, and possibly reduce surgically-induced endothelial cell damage.

Sonia Yoo, MD

However, it is discussed much less often that the safeguards built into FLACS instruments can fail and allow the femto laser grid pattern to be delivered into the cornea.

“We think this is what happened to one of my patients,” said Sonia Yoo, MD, professor of ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine. “Suction was lost during lens segmentation. The segmentation pattern that was intended for the lens nucleus unintentionally treated the cornea.”

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The good news is that the unintentional corneal scoring had no effect on the visual outcome, Dr. Yoo noted.

The patient had uncorrected 20/20 vision the day after surgery and still had 20/20 vision on her last exam a year after the incident. But because of the unexpected treatment of the patient’s cornea, she implanted a monofocal lens rather than the planned multifocal lens.

“The patient was quite happy with 20/20 vision,” Dr. Yoo said. “Even with the monofocal lens, her vision was so much better than it was pre-op that she was perfectly happy with the result. But this still points out that unexpected head movement can lead to suction loss and displaced laser beam delivery despite the safety mechanism of the femto platform. This is a potential development that you should discuss with your patient as part of your informed consent.”

Misplaced laser delivery

Suction was lost during lens segmentation. The segmentation pattern that was intended for the lens nucleus unintentionally treated the cornea. (Video courtesy of Sonia Yoo, MD)

Misplaced laser beam delivery is not a common occurrence. Dr. Yoo said she found just one similar event in literature, submitted by one of the session discussants, Samuel Masket, MD, Founding Partner of Advanced Vision Care and Clinical Professor of Ophthalmology at the Jules Stein Institute, David Geffen School of Medicine, University of California, Los Angeles. The common contributing factor to both events was patient movement. Dr. Yoo’s patient was moving so much she needed three attempts to dock and establish suction.

Once suction was established on the third try, the femto platform safety mechanisms should have detected the subsequent loss of suction and blocked the laser pulse. Instead, it appears that the conjunctiva occluded the suction holes, which prevented the platform from detecting the loss of suction and allowing the laser to fire after the eye had moved and delivering the segmentation pattern to the cornea.

Fortunately, the patient had a healthy Bell’s response and the eye had rolled up and out as she began to blink. The laser treatment was limited to the inferior third of the cornea and there was no damage to the central cornea.

“I don’t know if applying the segmentation pattern to the central cornea would have made a difference in post-op vision, but I was relieved we didn’t have to find out,” Dr. Yoo said. “More than a year out, I can still see that grid pattern on her cornea, but there have been no visual sequelae. Dr. Masket said he had a very similar case except that the grid pattern on his patient’s cornea faded over time.”

Identifying difficulties

The incident reinforces the need to identify patients who might present difficulties for laser treatment that might not be as significant for traditional phaco. Patients with deep-set orbits or very small eyes could be present challenges to femto laser treatment.

Patients who are unable to hold still can also be problematic. Deeper sedation is not a viable option, Dr. Yoo said. Not only must patients be alert, responsive, and able to focus on a bright light as directed during the procedure, they must also be able to move themselves in and out of a lying position for the instrument used in this procedure.

It is also important to realize that laser safety mechanisms can fail. While the laser should not be able to fire once suction is broken, it is possible that the device can sense suction even after the eye has moved if tissues such as the conjunctiva somehow occlude the suction holes.

Modifying the preoperative conversation and informed consent can be a useful strategy to deal with potential misadventures, she continued. The reality is that things do not always go as expected during any cataract surgery, not just FLACS. It particularly important to help the patient understand that surgical plans may change depending on how the procedure evolves.

“It is important to your pre-op discussion with the patient to explain that while you intend to use a laser and to implant a multifocal lens, there may be unforeseen circumstances which preclude the use of either and may require the use a monofocal lens in the interest of safety,” she said. “Safety for the patient is our first concern.”

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Reviewed by Jan Venter

Accidental perforation of the capsular membrane during surgery may cause posterior capsular rupture, leading to vitreous loss, which, in turn, may result in severe visual disability, cystoid macular oedema and retinal detachment.¹ Posterior capsular rupture is thought to occur in approximately 2% of cataract surgeries performed by skilled surgeons.² Although phacoemulsification is the standard of care in cataract surgery, it is commonly associated with posterior capsular rupture.

Innovations in phaco tip design

A potential risk factor for posterior capsule rupture is the design of the phaco needle. Typically, phaco needles are sharp in order to cut through the cataract. However, even the briefest encounter between phaco needle and capsule may lead to capsular rupture.³ Given the sight-threatening complications associated with this phenomenon, it is not surprising that phaco-needle manufacturers are designing tips with safety firmly in mind.

Early examples of efforts to improve tip safety included a design by Peter Davis, MD, who in the early 1990s developed a needle that had a rounded outer edge but retained a sharp inner edge. Joseph F. Gravlee, MD, created a needle with a blunted bevel. Takayuki Akahoshi, MD, devised the “knuckle tip”, which utilised a bulbous design with round edges on all surfaces.⁴

A more recent development in safe phaco-tip design is the Dewey Radius Tip (MicroSurgical Technologies, Redmond, Washington, USA), which was launched in 2006. The brainchild of Steven Dewey, MD, the Dewey Radius Tip represents considerable innovation in phaco-tip design. It incorporates radius edges on the inner and outer surfaces and is available in

thicknesses of 0.7 mm and 0.9 mm with a 30° bevel (Figures 1a and 1b). The inner and outer rims of the tip are rounded with exacting precision so there are no sharp edges to come into contact with the iris or the capsule, thus affording safer phacoemulsification. Dr Dewey notes that the Dewey Radius Tip behaves and functions exactly like a sharp-edged

phaco needle and is used in the same way; that is, no further training or modification in surgical technique is required. It can also be used on any patient and with any phaco machine, although older generations of phaco equipment might not be compatible.⁵

Figure 1a: 0.9 mm Dewey Straight Tip 30

Figure 1b: 0.7 mm Dewey Straight Tip 30

Safety

Safety of sharp versus “dull” tip design

I recently evaluated the Dewey Radius Tip in porcine eyes in order to determine the risk of capsular rupture compared with that of standard sharp-edged phaco tips. In the first part of this study, I used the Stellaris phacoemulsification platform (Bausch & Lomb, USA) with a 0.9 mm Dewey Radius Tip or a 0.9 mm sharp tip applied directly onto the capsular membrane with a vacuum pressure of 250 mmHg. I then delivered phaco power of increasing strength, from 0–100%, and noted the incidence of posterior capsule rupture.

In a group of ten eyes exposed to the 0.9 mm sharp tip, the posterior capsule ruptured in all cases – all at low phaco energy levels. Specifically, the posterior capsule ruptured at a phaco power of only 10% in five eyes and at a phaco power of 16% in the other five eyes. In contrast, with the 0.9 mm dull tip (Dewey), posterior capsule rupture occurred in only four of ten eyes, and then only when subjected to much higher phaco powers. Even at a phaco power of 75%, six capsules failed to rupture (Figure 2).

Figure 2: Posterior capsular rupture with a sharp versus a dull phaco tip (0.9 mm)

In the second part of the study, I compared the effects of the 0.7 mm Dewey tip with a Packard 0.7 mm tip (sharp) (MicroSurgical Technologies). All five eyes in the sharp-tip group had capsule rupture, again, even at low phaco powers (10–16%). In contrast, none of the eyes in the dull-tip group had capsular rupture, even at a phaco power of 75% (Figure 3).

Figure 3: Posterior capsular rupture with a sharp versus a dull phaco tip (0.7 mm)

Comparing new and old tips

Finally, I compared the effect of a used versus a new tip on posterior capsule rupture. The hypothesis was that a tip used many times becomes dull and, therefore, should cause less capsular damage than a new, sharp tip. Consequently, I exposed the capsular membrane of four eyes to a new AMO 21G Tip (Abbott Medical Optics, Inc, Abbott Park, Illinois, USA), and four eyes to an AMO 21G Tip that had been used 20 times previously. Interestingly, rupture occurred in all eyes in both groups at similar phaco powers (Figure 4).

Figure 4: Posterior capsular rupture with a new versus a used AMO 21G Tip

In another study, I compared what happened when the anterior capsule was contacted by a traditional sharp-edged tip and by the Dewey Radius Tip (0.9 mm, 30°) during torsional phacoemulsification with the Centurion system (Alcon, Fort Worth, Texas, USA).

The anterior capsule tests were conducted on six porcine eyes (per tip) at 70% and 100% torsional power. With the traditional sharp tip there was instant capsule rupture in all six eyes. In contrast, with the Dewey Radius Tip there was no anterior capsule rupture in any eye at either power setting. This suggests that the Dewey Tip also provides an increased level of safety in case of inadvertent contact with the anterior capsule.

Can tip type influence EPT?

Because reducing effective phacoemulsification time (EPT) is desirable in terms of minimising endothelial cell loss during cataract surgery, I compared EPT using the Dewey Radius Tip versus the standard sharp tip for a range of cataract grades. As expected, harder lenses required longer phacoemulsification. However, across all cataract grades, there was no difference in the EPT between tips (p=0.05). These findings suggest that the Dewey Radius Tip increases capsule safety without compromising performance.

There are few published studies evaluating the effect of tip design on capsular rupture, so it is difficult to discuss our study results within the context of others. However, our data echo early observations by Dr Dewey and colleagues, who assessed the Dewey tip in cadaver eyes and found that they could apply 50% phaco power at 400 mmHg vacuum for extended periods before the capsule ruptured.⁴ Overall, these findings suggest that using a rounded phaco tip increases the safety of phacoemulsification, thus helping to reduce the burden of complications to both cataract surgeons and – more importantly – to patients.

References

1. M. Zare et al.,J. Ophthalmic. Vis. Res. 2009; 4: 208-212.

2. D.F. Chang. Cataract & Refractive Surgery Today February 2012.

3. E. Stodola. ASCRS EyeWorld March 2014.

4. S.H. Dewey. Ocular Surgery News October 2007.

5. J. Helzner. Ophthalmology Management December 2008.

Kotaro Oki, MD, PhD

E: kotaro-o@pc4.so-net.ne.jp

Dr. Kotaro Oki, PhD, is an ophthalmologist in practice at the Oki Eye Surgery Center, Tokyo, Japan. He states that he has no financial interests in MicroSurgical Technologies.

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Los Angeles—Scleral suture fixation of the IOL-capsular tension ring (CTR)-capsular bag complex is an effective option for surgical repositioning of a dislocated IOL, according to Robert K. Maloney, MD.

“Considering the utility of this approach, surgeons should have a low threshold for placing a CTR during cataract surgery in eyes at risk for IOL dehiscence, such as those with pseudoexfoliation or a traumatic cataract,” said Dr. Maloney, Maloney Vision Institute, Los Angeles, and clinical professor of ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles.

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Dr. Maloney described the technique by discussing a case of a patient he saw on referral about four years after successful phacoemulsification and IOL implantation with a CTR in the right eye. Six years prior to cataract surgery, the patient had sustained a ruptured globe secondary to blunt trauma. The rupture was repaired, but the iris that prolapsed through the rupture remained incarcerated following the surgery. The pupil was also distorted.

The patient presented to Dr. Maloney with classic sunset syndrome, best-corrected visual acuity (BCVA) of 20/40, and complaints of blurred vision, a severe glare, and the inability to drive at night.

Reviewing potential approaches for managing the dislocated IOL, Dr. Maloney said he ruled out an anterior chamber IOL due to the iris defect. He also decided against using the glued IOL technique after removing the CTR-capsule bag complex given the challenge of performing the latter step.

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“Suturing around the CTR to the sclera seemed to be the natural solution, but the patient’s original surgeon was worried about suturing through the prolapsed iris, which was incarcerated in the old scleral rupture,” he said. “That was not a concern for me because my plan was to create the sclerotomies 3 mm posterior to the limbus in order to suture through the pars plana.”

(Preop: Video 1 of 2) A classic sunset syndrome, with the edge of the optic barely visible above the pupil. the capsule tension ring makes an arc across the pupil at the edge of the capsular bag. There is a sectoral iris defect superonasally with iris remnant visible subconjunctivally where it prolapsed through the scleral rupture. Video Courtesy of Robert K. Maloney, MD

After removing the conjunctiva...

(Postop: Video 2 of 2) On postop day 2, the IOL is well centered on the limbus. There is an aphakic space superiorly in the area of the iris defect. The whitish hue is due to the intraoperative use of triamcinolone acetate to identify vitreous strands. Video Courtesy of Robert K. Maloney, MD

After removing the conjunctiva from the area of the planned sclerotomies, he marked two sclerotomies superonasally, 3 mm apart and 3 mm back from the surgical limbus overlying the pars plana. One of the sclerotomies was made with a 1.0-mm blade. A needle with 8-0 Gore Tex suture attached was then passed through the other mark, around the CTR and withdrawn from the eye through the primary incision.

The needle was cut off and the suture was passed back through the previously opened sclerotomy with a handshake technique. The same procedure was used on the opposite side of the IOL-capsular bag complex to secure it. Both sutures were tightened and tied episclerally, and the knots rotated through the sclerotomies to bury them.

“It is relatively easy to pass a needle through the scleral wall and then through the capsular bag,” Dr. Maloney said. “For me, this is easier than passing the needle in the opposite direction, where a blind scleral pass is needed.”

It is important not to leave suture knots on the episclera because these knots can erode over time. A Hoffman pocket can be used, but is challenging to make, he noted.

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“Instead, I rotated the knots through the sclerotomy, a technique I learned from Nicole Fram, MD,” Dr. Maloney explained. “Rotation of the knots was possible here because the sutures was not knotted around the CTR.”

At follow-up two days after surgery, the lens was well centered on the limbus, and at six months, the patient had 20/25 BCVA without any glare or night-driving issues.

This article is based on a presentation given by Dr. Maloney at the 2015 meeting of the American Academy of Ophthalmology. Dr. Maloney has no relevant financial interest to disclose.

Cataract surgery appears to reduce the risk of glaucoma in eyes with pseudoexfoliation (PEX) syndrome, researchers said.

“The present study indicates that there should be a rather low threshold for performing cataract extraction in PEX eyes with regard to the risk of developing glaucoma,” wrote Olav Kristianslund, MD, MPh, resident in ophthalmology, PhD-student, and colleagues from Oslo University Hospital and the University of Oslo, Norway.

They published their findings in Acta Ophthalmologica.

Pseudoexfoliative material apparently clogs the trabecular meshwork, Schlemm’s canal, and collector channels, elevating IOP and making PEX syndrome the greatest risk factor for glaucoma.

Several studies have shown that cataract surgery lowers IOP in eyes with or without PEX syndrome, the authors reported, but they were unable to find any research comparing glaucoma development after cataract surgery under these two conditions.

To fill this gap, they analyzed data from patients recruited for previous studies who had cataract surgery between June 2001 and December 2002 at Oslo University Hospital. From 1,193 patients, they found 51 with PEX syndrome who were still living in the Oslo area in 2008 and able to participate. They compared these with 102 controls.

Patients in both groups had a mean age of 82.4 years at the time of re-examination and a majority, 72.5%, were female. The mean time from cataract surgery to re-examination was 76 months.

At baseline, 16 (31%) of the patients with PEX had glaucoma, compared with 10 (19%) of the patients without glaucoma. The mean IOP at baseline was 16.5 mm Hg in the PEX group and 15.7 mm Hg in the control group.

In each case, surgery consisted of a sutureless small limbal incision, a capsulorrhexis, hydrodissection, and phacoemulsification, followed by the insertion of a foldable IOL using forceps.

Surgeons placed the IOL in the capsular bag in almost all these patients, except two in the PEX group and 10 in the control group who had the lens placed in the ciliary sulcus.

Re-examination

At re-examination, one additional patient in each group had glaucoma, bringing the total to 17 (33.3%) in the PEX group and 11 in the control group (10.8%). This corresponds to an incidence of 0.47 cases per 100 person-years in the PEX group, versus 0.17 in the control group.

The authors compared these rates with those in a population-based study (Acta Ophthalmologica Scandinavica 2007, 85: 832-837) of 2.1 per 100 person-years for patients with PEX and 0.5 for patients without the syndrome. Only 21% of patients had cataract surgery during the follow-up time. Other population studies in patients of this age have found similar results.

Both groups in the present study experienced a significant decrease of IOP, reaching 14.0 mm Hg in the PEX group and 13.9 mm Hg in the control group at re-examination.

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Spikes in IOP were significantly more frequent in the PEX group than in the control group, as well as in the patients with glaucoma compared with those without.

A possible explanation for the pressure-lowering effect of cataract surgery is that the removal of the biological lens and the central anterior capsule reduces the release of pseudoexfoliative material and pigment, Dr. Kristianslund and his colleagues wrote. In addition, this material is washed out during the surgery.

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The researchers acknowledged some limitations to their study.

First, the baseline data was extracted retrospectively.

Secondly, they did not verify known glaucoma cases or search for new ones using objective glaucoma measurements, although all the study participants underwent extensive examinations.

Finally, the population of the study was small for calculating incidence rates.

Still, the authors argued that their findings have significant implications.

“Our results indicate that phacoemulsification cataract extraction is protective against the development of glaucoma in the longer term, especially in PEX eyes,” they concluded.

Florence Cabot, MDOphthalmologists spend significant amounts of time during cataract surgery trying to precisely center an implanted IOL to achieve the best possible vision after surgery. The high success rate of cataract surgery suggests that in most cases, they succeed.

But there have been long-nagging questions about IOL movement within the capsular bag after cataract surgery. Some data suggest that IOLs may shift position by 500 µm or more following surgery–a sufficient drift to degrade vision. However, results from what may be the largest study of IOL stability in the 30 days following implantation suggest that once implanted, IOLs tend to remain within 200 to 300 µm of the original position.

“We found that the center of both monofocal IOLs and toric IOLs is essentially unchanged from day 1 after cataract surgery to 30 days after surgery,” said Florence Cabot, MD, senior research associate, Bascom Palmer Eye Institute, University of Miami. “Furthermore, we did not see any difference in IOL centration between manual cataract surgery and femtosecond laser procedures between day 1 and 30 days postop.”

Day 1, Day 30 data

Day 1, day 30 data

Researchers measured the centration of 59 eyes in 49 patients day 1 after surgery and 1 month after surgery using iTrace Ray Tracing technology. IOL centration was measured relative to 3 distinct landmarks–the center of the pupil, the center of the limbus, and the corneal apex.

Figure 1. iTrace scan of the IOL centration.

A total of 45 eyes received a monofocal IOL and 14 eyes received a toric IOL. Just over half of the surgeries (32) were performed using traditional techniques and 27 were performed using femtosecond laser assisted cataract surgery (FLACS).

The final results were similar for both monofocal and toric IOLs, as well as for conventional and FLACS procedures, Dr. Cabot reported. For lenses implanted using conventional techniques, there was a mean supero-nasal shift of 293.80 µm relative to the pupil center and no trend relative to the limbus center or to the corneal apex. For FLACS procedures, there was a mean infero-temporal shift of 218.75 µm and no trend relative to the limbus center or the corneal apex.

Figure 2. FLACS infero-temporal IOL shift relative to pupil center: IOL shift between POD #1 and POM #1 relative to pupil center (A), limbus center (B), and vertex (C).

The findings are important in two areas, Dr. Cabot said. First, it should be reassuring to both surgeons and to patients that while there is a shift in IOL centration between day 1 and 1 month after surgery, the shift is small–200 to 300 µm. And while the shift can be measured reliably, it is unlikely to have any clinical effect on visual acuity or on patient satisfaction with the procedure and its outcome.

Reassuring data

Reassuring data

The findings should also be reassuring for surgeons in that both dominant technologies–conventional cataract surgery and FLACS–produce similar centration results whether the patient receives a monofocal IOL or a toric IOL. With either procedure, the shift in centration over the 30 days following surgery is detectable using ray-tracing technology, but the shift appears to be small and not clinically significant.

“There has been some concern about the optimization of cataract surgery for multifocal IOLs somehow requiring the use of a femtosecond laser system,” Dr. Cabot explained. “We did not see any clinically significant difference in results from day 1 to day 30 in lens centration from using FLACS compared to conventional cataract surgery or between monofocal and toric IOLs. We would all like to see further studies to confirm these results with multifocal IOLs.”

Figure 3. Traditional cataract surgery supero-nasal IOL shift relative to pupil center: IOL shift between POD #1 and POM #1 relative to pupil center (A), limbus center (B), and vertex (C).Ray-tracing technology has obvious limitations, she continued. That suggests using other technologies, such as high-resolution optical coherence tomography (OCT) or a Scheimpflug camera, such as the Pentacam, to confirm the results with a richer data set.

It would also be helpful to add a third data collection point immediately after surgery. Ophthalmologists typically spend a few minutes positioning IOLs and, in the case of toric lenses, rotating the IOLs for optimal visual effect. It is widely recognized that the capsular bag may contract asymmetrically in some individuals, but little is known about why or when that contraction occurs.

The single largest unknown may be positioning changes that take place in the hours immediately following surgery. Dr. Cabot said that adding an intraoperative evaluation of IOL centration could help ophthalmologists evaluate the effect of early changes compared to day 1, 30 days, and possibly longer after surgery.

Florence Cabot, MD

E: fcabot@med.miami.edu

Dr. Cabot thanked her co-investigators on the study: Adbul-Hadi Kaakour, MS; Matthew Donovan, BS; Carolina de Freitas, MS; Nilufer Yesilirmak, MD; Vasilios Diakonis, Bilian Ke, MD; Sonia H. Yoo, MD; and Anat Galor, MD.

This article is adapted from Dr. Cabot’s presentation at the 2015 American Society of Cataract and refractive Surgery meeting.

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Surgeons are urged to take a more cautious approach to cataract surgery when a new, pre-existing rupture of the posterior capsule surfaces.

For example, it is important to gently remove the nuclear material first while the cortex is still in place, said Gregory S.H. Ogawa, MD. The cortex can act as a scaffold, or splint, to help maintain support posteriorly.

Dr. Ogawa, cornea and complex anterior segment specialist, Eye Associates of New Mexico, and assistant clinical professor of ophthalmology, University of New Mexico, Albuquerque, described the challenges associated with such a case.

A retina specialist was treating a 56-year-old patient for a vitreous hemorrhage. After performing a pars plana vitrectomy and peeling scar tissue on the retina, the specialist prepared to cauterize a bleeding vessel. At that moment, the patient turned his head, causing the cautery probe to pierce the nasal portion of the lens. A cataract rapidly ensued, obscuring the view of the posterior segment.

While some situations involving a posterior capsule rupture can be addressed weeks or months while the capsule begins to fibrose and to be less prone to splitting, the retina specialist in this case wanted to promptly view the posterior segment so cataract surgery could not be delayed.

To watch Dr. Ogawa perform this procedure, click here to skip to the last page.

Day 1 post-op exam

Dr. Ogawa examined the patient the next day. He found a dense posterior subcapsular cataract across the nasal two-thirds of the posterior portion of the lens, with a white feathery pattern. A linear track from the cautery probe was visible from near the center of the posterior portion of the lens tracking inferonasally.

Both the patient’s eyes had histories of retinal tears and 12 years earlier, he had LASIK treatments. However, the main issue was the split in the posterior capsule.

The following day—two days after the pars plana vitrectomy—Dr. Ogawa operated to remove the cataract and implant an IOL.

“The whole surgery was done gently, trying to lift the cataract material up and out as opposed to standard phacoemulsification with pressure down on the lens while it is removed,” Dr. Ogawa said. “If I had done a regular cataract procedure, it is very likely that all the nuclear material would have dropped to the back of the vitrectomized eye.”

Dr. Ogawa proceeded with a scleral tunnel incision, which can be enlarged without inducing a lot of post-operative astigmatism.

“If it had been needed, I could make a larger incision that could still be stable after the surgery, yet be large enough to be able to take out bigger pieces of lens material,” Dr. Ogawa explained. “In this particular case, I was able to aspirate all the lens material. If it was a denser nucleus, I would have needed to remove it manually through a larger incision, or through a small incision using an extremely gentle phacoemulsification technique.”

Dr. Ogawa used a low-flow set-up with a limbal infusion cannula and a manual cortex aspirator (his own invention), along with an IOL manipulator to physically lift the nucleus anteriorly after a careful hydrodelineation around the nucleus. After removal of the nucleus, he removed the cortex from the periphery prior to removing central cortex to minimize how much lens material might go posteriorly when the capsule no longer had support and split open further.

Dr. Ogawa kept the bottle height at about 30 cm in contrast to the 70 or 105 cm height typical for phacoemulsification cataract surgery. “With doing things this way, I could do everything more slowly and be able to lift material anteriorly in a more controlled fashion,” he added.

No hydrodissection

Video Courtesy of Gregory S.H. Ogawa, MD

No hydrodissection

Dr. Ogawa did not use hydrodissection, which would have sent the fluid behind the lens, creating pressure on the ruptured posterior capsule with the chance of splitting it wide open with posterior loss of the cataract. Instead, he used only hydrodelineation, injecting fluid between cortex and nucleus to make it easier to remove the nucleus while the cortex stayed in place.

The traction on the central capsule during removal of the last cortical pieces triggered a complete split of the posterior capsule, allowing a small piece of cortex to drop to the posterior pole.

Dr. Ogawa used a flat surface Machamer-style irrigating contact lens to inspect the posterior segment. With the lens for visualization, he was able to remove the lens material with a vitrectomy probe through a limbal paracentesis.

Finally, he implanted a STAAR AQ2010V IOL (STAAR Surgical) in the sulcus. “This lens has a 13.5-mm overall diameter, so it is big enough to be relatively stable in the sulcus,” he explained.

Dr. Ogawa selected a silicon lens with small, round haptics and rounded optic edges because acrylic lenses with squared edges on the optic and haptics can rub on the iris, causing pigment dispersion, inflammation, and IOP elevation.

Upon follow-up a year after the procedure, the patient’s vision was 20/40 uncorrected in this eye, and with minimal refractive correction, the vision was 20/25.

Gregory S.H. Ogawa, MD

e: gogawa@eyenm.com

This article is adapted from Dr. Ogawa’s presentation at the 2015 American Society of Cataract and Refractive Surgery meeting.

Reviewed by Jorge Alio

Cataract surgery in patients with small pupils is associated with a raft of complications including damage to and prolapse of the iris into a wound, the creation of a small anterior capsulorrhexis (leading to anterior capsule damage), incomplete removal of the cortical material, postoperative inflammation and a higher risk of posterior capsule rupture.^1,2

A small pupil also hampers visualisation of the peripheral capsule, making it difficult to ensure that the lens and haptics are placed completely in the bag.

Achieving and maintaining adequate mydriasis is crucial in preventing serious complications. However, we are fortunate to have more interventions and instruments available than ever before to help us deal with these difficult cases.

Managing small pupil size

There are a number of options for increasing pupil size, including the use of intracameral mydriatics such as Shugarcaine and epi-Shugarcaine, viscodilatation and pupil-expansion devices. The pupil-expansion devices available include plastic and metal iris hooks, Clarke and Siepser rings, the Graether expander (Eagle Vision Inc.), the 5S iris ring (Morcher GmbH) and Perfect Pupil (Milvella Pty Ld), to name just a few.

In the past, I nearly always used iris hooks in patients with small pupils. However, for my difficult cases, including patients with intraoperative floppy iris syndrome and pseudoexfoliation syndrome, I now almost always use the Malyugin ring (MicroSurgical Technology, Inc.).

The brainchild of Boris Malyugin, professor of ophthalmology and deputy director general at the S. Fyodorov Eye Microsurgery State Institution in Russia, the Malyugin ring was designed to overcome some of the disadvantages associated with other pupil expanders, such as overstretching of the iris sphincter and extended surgery time. The Malyugin ring is a square-shaped device made from 5/0 polypropylene with a paperclip-scroll design that holds the iris at eight equidistant points.

The result is a round pupil, rather than the square one formed with four iris hooks, and circumferential protection of the iris (Figure 1). Helpfully, the device is available in two sizes, 6.25 mm and 7.00 mm, which offers a degree of flexibility. For example, while the 6.25 mm ring is suitable for most cases, the 7.00 mm ring is more suitable when placing an IOL with a large-diameter optic, or for surgeons who use the divide-and-conquer technique.

Key advantages

Key advantages of the Malyugin ring

As noted earlier, I used to employ iris hooks during cataract surgery in patients with small pupils. In doing so, it was necessary for me to create four or five corneal incisions.

Although I never experienced any problems with hooks, there is the risk that they might overstretch the iris sphincter and create iris defects. The main advantage of the Malyugin ring is that it can be inserted via the main clear corneal incision, eliminating the need for multiple incisions.

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There is no need to widen the main incision. I use a 2.2 mm incision and can easily place the Malyugin ring through it. This obviously saves considerable surgical time and is less invasive than using iris hooks.

The Malyugin ring also eliminates stretching or distorting of the pupil. Because it affords minimal contact with the iris, it is less likely to damage the iris sphincter than other rings or hooks. Perhaps not surprisingly, I no longer turn to hooks when I need to perform mechanical pupil expansion.

The Malyugin ring is very easy to use thanks to its disposable injector, which aids placement of the ring around the edge of the pupil. Typically, the first three of the four paperclip-like scrolls are very easy to insert.

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However, to facilitate insertion of the fourth scroll close to the main incision, I would advise using the injector and an Osher micromanipulator (MicroSurgical Technology, Redmond, WA), which is designed for the specific geometry of the Malyugin ring, through a second incision.

After surgery, the same Osher micromanipulator can be used to remove the twelve o’clock scroll, while the injector can be used to quickly and smoothly remove the ring without trauma to the iris sphincter (Figure 2). Unlike other pupil-expansion devices, the injector can be disposed of once surgery is complete, eliminating the need for sterilisation and its associated costs.

Additional tools

Additional tools

Of course, I also use other pupil expanders and hooks, although perhaps less frequently than the Malyugin ring.

Alcon iris hooks (Alcon Laboratories, Inc., Fort Worth, TX) are useful in specific cases where I need to open the iris locally rather than globally. In cases of traumatic damage, some local pupillary defect or iris desinsertion may happen and iris hooks help ensure safer cataract surgery.

Thankfully, small pupils are not very common so, for most surgeons, the need for hooks and mechanical dilators such as the Malyugin ring is somewhat limited.

However, to date and in my experience, the use of the Malyugin ring appears to be safe without any intraoperative difficulties or complications observed.

It undoubtedly provides greater confidence to the surgeon in offering safer and more effective cataract surgery to patients with small pupils.

References

1. J.D. Bartlett and K.M. Miller. Compr. Ophthalmol. Update 2003; 4: 171-176.

2. Malyugin B. Cataract Refr. Surg. Today Europe. 2013: 26-30.

Cedric Schweitzer, MD, is an ophthalmologist based at the University Hospital Bordeaux in France. Dr Schweitzer has no financial interests in MicroSurgical Technology, Inc.

E: cedric.schweitzer@chu-bordeaux.fr

Reviewed by Stephen G. Slade, MD

Take-home message: A new image-guided system streamlines surgical planning for patients undergoing cataract surgery with implantation of a single-piece aspheric IOL or a multifocal IOL.

Houston—Using a new image-guided system (Verion Image Guided System, Alcon Surgical) to plan cataract surgeries with implantation of a single-piece aspheric or multifocal IOL resulted in low residual refractive cylinder and good accuracy to target and refractive outcomes.

More Cataract: Premium cataract surgery-correcting complications and side effects

These initial results indicate the image-guided system is a valuable addition to the cataract surgery toolkit.

Stephen G. Slade, MD, and Kerry Solomon, MD, evaluated the system in an open-label, prospective, non-randomized, multicenter study that included 188 eyes.

All patients underwent femtosecond laser (LenSx)-assisted cataract removal during phacoemulsification. Any preoperative astigmatism was treated with astigmatic keratotomy.

Eighty-eight patients were implanted with a single-piece aspheric monofocal IOL (SN60WF, Alcon), and 100 patients were implanted with a multifocal IOL (AcrySof IQ ReSTOR IOL, Alcon).

The residual refractive cylinder, postoperative manifest refractive spherical equivalent (MRSE) accuracy to target, and the best-corrected distance visual acuity (BCDVA) (exploratory efficacy results) were recorded at three months postoperatively, according to Dr. Slade, private practice, Houston.

Recent in Cataract News: How Big Data is changing the game in cataract surgery

The primary study objection was evaluation of the clinical results as measured by the percentage of the study population with 0.5 D or less of residual refractive cylinder three months postoperatively.

The secondary objectives were assessment of the outcome of the manifest refraction spherical equivalent (MRSE) compared with the targeted outcome of 0.5 D or less and a comparison of the keratometry readings, mean corneal curvature, and magnitude of astigmatism and description of the axis measured preoperatively.

Outcomes

Primary, secondary outcomes

At the 3-month evaluation, 62.1% and 82.8% of patients with the monofocal IOL implanted had a residual refractive cylinder of 0.50 D or less and 0.75 D or less, respectively.

Of patients with the multifocal IOL implanted, 71% and 88% had a residual refractive cylinder of 0.50 D or less and 0.75 D or less, respectively.

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In comparison, Dr. Slade said the results published by surgeons who manually use an advanced IOL power formula, calculate the surgically induced astigmatism, and perform meticulous ink-marking showed that 53.3% of a toric population achieved 0.50 D or less of residual refractive cylinder (Holland et al. Ophthalmology. 2010;117:2104-2111).

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Regarding the secondary outcomes in the monofocal IOL group, 77% had a MRSE of 0.50 D or less and 97.7% were within 0.75 D or less accuracy.

In the multifocal IOL group, the results indicated that 82% had a MRSE of 0.50 D or less and 94% were within 0.75 D or less accuracy.

Exploratory efficacy outcomes

At the 3-month evaluation of the monofocal IOL group, 62.1%, 86.2%, and 98.9%, respectively, had best-corrected distance visual acuity of 20/20 or better, 20/25 or better, and 20/30 or better.

In the multifocal IOL group, the percentages were 62%, 92%, and 98% for the respective visual acuity levels.

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Investigators concluded that the system is a valuable addition to surgical planning.

Dr. Slade concluded that study results showed patients had low residual refractive cylinder and good accuracy to target and refractive outcomes when using the image-guided system for surgical planning on patients with different IOL platforms.

Stephen G. Slade, MD

E: sgs@visiontexas.com

This article was adapted from Dr. Slade’s presentation at the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Slade is a consultant for Alcon Laboratories.

Gloves Off with Gulani By Arun C. Gulani, MD

Take-home message: In this third of a three-part column, Arun C. Gulani, MD, continues the discussion correcting premium cataract surgery.

This final part of the designing cataract surgery series addresses methods to correct complications and side effects of premium cataract surgery, including patient dissatisfaction postoperatively.

For simplification, I have devised a classification system based on more than two decades of correcting complications associated with cataract surgery in patients from around the globe and categorized the system for simplicity in understanding the core issue—patient perception of the problem—and thereby unfolding the specific plan of action.

Gulani Cataract Complication Analysis:

I. Surgery related complications

a. Anatomic-like corneal damage, iris damage, etc.

b. Inflammation

c. Optical pathway (i.e., pupil, lens centration, etc.)

II. IOL-based problems

a. IOL power

b. IOL optics in relation with corneal optics

c. IOL defects (broken/cracked/subluxed)

III. Patient symptomatology and dissatisfaction

1. Dysphotopsia (IOL capture)

2. Glares/haloes, etc.

3. Psychological

I. Surgery-Related Complications

Complications associated with cataract surgery can be linked to the surgery itself in that the surgery can have resulted in anatomic damage in the corneal, iris, or vitreoretinal tissue. There may also be combinations of these directly or indirectly.

Additionally, surgery can cause inflammation that can decrease the visual outcomes, i.e., cystoid macular edema, and even involve adjacent anatomy-related optical pathway like decentration of the lens implant relative to pupil centration and thus the resultant visual symptoms. When the vision is impacted negatively, this in turn affects patient satisfaction.

Anatomic damage can be corrected in the appropriate sequence, as I described in previous columns, keeping in mind the least-interventional Corneoplastique techniques for restoring the anatomy in planning for the optimal optical outcome.

Inflammation can be appropriately and aggressively treated to resolution while optical pathway incoherence can be addressed in pupil-IOL relations with many approaches, the most minimal of which could be the Donnenfeld Argon Iris Laser (at the site of the decentered pupillary edge) technique.

II. IOL-based complications

II. IOL-based complications

These problems can be related to defective IOLs, such as broken haptics and damaged optics, which resulted from a manufacturing issue or from handling before or during surgery (while loading or manipulating the lens). In such cases, an IOL exchange can be performed safely to restore the visual quality.

Poor vision also can result from a less-than-optimal choice of IOL based on determining the angle kappa, spherical aberrations levels, refractive errors, and corneal irregularities and not matching them with the correct optic of the appropriate IOL.

Further, the IOL implant often may be incorrect in its emmetropic outcome, in that the patient may be over-corrected or under-corrected with or without associated astigmatism.

Keeping Corneoplastique principles in mind, the IOL can be exchanged for another properly calculated IOL or a laser surface ablation technique or a piggyback technique performed as previously described in stage-2 surgeries to achieve an optimal optical endpoint.

III. Patient symptomatology and dissatisfaction

In some cases, patients may not have been adequately educated about and prepared for the visual outcomes, which the surgeon may deem to be perfect. In addition, the surgeons’ anticipated desires and profession-related endpoints and other confounding factors may negatively impact patient satisfaction postoperatively.

Some patients can be negatively or psychologically affected or unprepared for improper or unexpected endpoints such as glare and halos. They may find relief only with exchange of the IOLs.

Case scenarios

Case scenarios

These case scenarios represent the application of logic-based principles of Corneoplastique, in applying the least interventional, brief, topical, elegant, and visually promising techniques to achieve the best visual potential (BVP) while striving in most cases to honor the original surgeon’s standing and choice of technology.

Case 1 was that of a patient who was referred to me after undergoing implantation of a multifocal IOL with a poor and unsatisfactory visual endpoint. The patient’s surgery after implantation of a multifocal lens had resulted in an IOL surprise. It followed with multiple laser and LASIK enhancements that ended in corneal scarring with a final vision of 20/200. In addition, this patient also underwent YAG capsulotomy. The patient was extremely angry with her surgeon and concerned as a result of the surgeries and poor visual outcome.

Following my 5S system, I first wanted a “measurable” cornea and hence performed laser PRK with scar peel (on-cornea scar) to correct the scarring and achieved a clear measurable cornea that refracted to a hyperopic endpoint of +6.00 diopters with best-corrected vision of 20/25.

Now, as planned, I was aiming to correct this measurable and accurate refractive error so a lens-based correction was the path that I zeroed down to. Considering the fact that this patient had undergone a YAG capsulotomy and therefore this lens implant could not be exchanged without detrimental maneuvers, I planned a piggyback lens implant (the Corneoplastique principles were maintained: brief, topical, aesthetically pleasing, least interventional, and visually most promising) and brought this patient to 20/20 unaided for distance and near vision.

Case 2

Case 2 was that of a patient who was referred with a dense central corneal scar after a previous RK procedure and recently having undergone cataract surgery. The on-cornea scar in many of these cases can be peeled off in the right plane resulting in improved vision (without need for any transplant) and he was already pleased with his vision so much that he differed the planned laser corneal advanced surface ablation surgery (ASA) to emmetropia.

Another patient was referred by his eye surgeon following implantation of an accommodative IOL in an eye treated previously with RK. Before a knee-jerk reaction of exchanging the implant, I always look at refractive errors and offer simulation to look for symptomatic improvements (BVP).

Once the ocular surface is corrected, the refractive errors can be addressed using surface laser ASA (the new-carpet-over-broken-tiles approach) and achieve visual satisfaction.

Most patients with RK—and for that matter any previous corneal surgeries who have bad endpoints after multifocal and premium IOL implants—usually have some residual refractive error, most often astigmatism.

I encourage surgeons to make sure that the refractive endpoint is always neutral before blaming the IOL implant. These cases can be corrected easily with corneal refractive surgery to excellent endpoints, thus maximizing the impact of the premium lens implant to achieve optimal vision.

Case 3

Case 3 was that of a patient referred to me who had undergone a multifocal lens implant with her surgeon and she was unhappy with her vision. I include this case to demonstrate the psychological impact on patients, because I do not succumb to a knee-jerk reaction to remove an IOL and blame the previous surgeon unless I have run out of my mental thought process of salvaging vision with that IOL before embarking on any surgery.

After treating her obvious dry eye, I refracted her and determined her astigmatism to be stable, and on simulation she found improvement in her vision with that correction. We then proceeded with laser vision surgery and she was now 20/20 in this eye.

She noticed improved vision but came back to me with her husband saying she was still angry at her previous surgeon for not explaining haloes and glare that could occur with this lens implant and hence wanted it removed. The interesting factor in this case is she had no such symptoms even on subjective testing and simulations and she herself admitted to not really having the symptoms described in a Google search.

After an extensive discussion with me and her husband, she understood how much her vision had improved and that she had no such symptoms which she had read online about. She called me twice and we had lengthy conversations and every time she agreed that she was just paranoid it can happen to her and would thank me for her improved vision of 20/20.

A month later she called again and said she had determined to have this lens implant removed. It was, she described, “agonizing” for her to live with something that could cause symptoms that she read about online and her surgeon should have at least educated her, let alone warned her.

She travelled back to me and after another detailed consultation (during which she explained her agony) and informed consent (remember she was 20/20 now) I agreed to remove her multifocal lens and maintain her 20/20 vision using a monofocal lens implant. The next day after surgery she was 20/20 and very happy and relieved.

An example of a case where psychologically a patient can actually feel so traumatized by what she felt was a “time-bomb” in her eye just because of her anger toward her surgeon. A lawsuit was averted and relations corrected.

In summary

In summary, no matter what the cause of a patient’s unhappiness after premium cataract surgery, it is in most cases possible to correct both the vision and the relation of the patient in question and their surgeon using a logic-based approach as described in this column.

In the next column, I will address keratoconus as a refractive surgery—thinking outside the cone—a mindset that will revolutionize how surgeons look at and treat one of the most commonly blinding conditions in eye care.

References

Gulani AC. Femtosecond Laser in Refractive Lens Exchange: Surgical Treatment for Presbyopia. Wang M, ed.; Slack Inc., Thorofare, NJ; 2016;109-115.

Gulani AC. Corneoplastique: Art of LASIK & cataract surgery. Ind J Ophthalmol. 2014;62:3-11.

Gulani AC. Evaluating the impact of femto laser-assisted capsulotomy. Cataract Refract Surg Today Europe. 2014;9:36-50.

Gulani AC. Shaping the future and reshaping the past: the art of vision surgery. Chapter 98. In: Copeland and Afshari’s Principles and Practice of Cornea. New Delhi, India: Jaypee Brothers Medical Publishers, 2013;2:1252-1273.

Donnenfeld E, Gulani AC. Astigmatism correction during cataract surgery. In: Garg H, Alió JL, eds. Femtosecond Laser: Techniques and Technology^,1st ed. Miami, FL: JayPee Highlights Medical Publishers; 2012;21:155-161.

Arun C. Gulani, MD, is founding director and chief surgeon of the Gulani Vision Institute, Jacksonville, FL. Dr. Gulani has no financial interests to declare.

Take-home: An approach is described for completing cortex removal and IOL implantation after intraoperative 180° zonular dialysis.

Toronto, CA—When an overly aggressive attempt to remove tenacious cortex results in iatrogenic zonular dialysis, the first priority for the cataract surgeon should be to take steps to maintain capsule integrity and avoid vitreous prolapse. Removal of residual cortex is also important for the final outcome.

Options for management might include cautious endocapsular phacoemulsification by itself, conversion to extracapsular surgery, capsular retractors, implantation of a capsular tension ring (CTR), and use of a sutured capsular tension device.

More Cataract: Image-guided system streamlines cataract surgery planning

The decision, however, will be best made through careful assessment of the situation once the eye is stabilized, said Iqbal (“Ike”) Ahmed, MD.

In an intraoperative video, Dr. Ahmed, assistant professor of ophthalmology and vision sciences, University of Toronto, Ontario, Canada, presented his approach to managing this “disinsertion dilemma” in a case involving a 180° zonular dialysis.

Premium Cataract Surgery: Correcting complications and side effects

The patient did not have pseudoexfoliation or other risk factors for zonular weakness, and the surgery was proceeding uneventfully until cortex removal. As the operating surgeon persisted in trying to remove residual cortex, the capsule was aspirated into the instrument tip, resulting in 180° of nasal zonular dialysis with retained cortex in the capsular bag. Fortunately, the capsular bag remained intact, Dr. Ahmed said.

After stopping the procedure and while keeping the I/A tip in the eye, a cohesive ophthalmic viscosurgical device (OVD) was instilled to reform the anterior chamber and stabilize the eye.

Dr. Ahmed offered several tips for completing this initial step.

Tips

“It is important to keep the I/A instrument in place because if the capsule has been aspirated into the tip, removing the hand-piece from the eye could bring the entire capsular bag too,” he said.

The injected OVD can serve to displace any aspirated capsule from the tip, but before OVD is injected, infusion should be stopped or else the injected material will come back out from the incision site. At the same time, surgeons need to be careful not to overfill the eye as that will also cause OVD to leak out of the incision, and vitreous prolapse may follow.

Recent Cataract: Clinical experience with a mechanical pupil dilator

Once the I/A tip was freed of material and the chamber stabilized, examination showed the residual cortex was present primarily in the superior area of the capsular bag, well away from the site of the zonular dialysis.

Considering that use of an automated technique for completing cortex removal could create an unstable situation, Dr. Ahmed chose a manual approach to cortex aspiration, using a 27-gauge hockey-stick cannula to irrigate and aspirate the residual cortex.

Recent: Overcoming challenges of pre-existing ruptured posterior capsule

“It is important to add a few boluses of irrigation that will not only help with cortex removal but will also keep OVD away from the cannula,” he said.

After completing cortex removal, Dr. Ahmed said he was comfortable in this case placing a CTR to stabilize the capsular bag, taking into account the location of the zonular dialysis, its extent, and anticipating that it was stationary, i.e., non-progressive.

Continued

“My limit for using a standard CTR is up to six clock hours of localized zonulysis, assuming the remaining zonules are in good shape. In that setting, the CTR is quite effective in distributing forces around the entire capsular circumference,” he said. “In addition, the dialysis in this eye was 180° away from the incision, which enabled injection of the CTR into the area of weakness. That would have been more difficult if the dialysis was located temporally.”

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Dr. Ahmed said he removed cortex first rather than starting with placement of the CTR as the latter sequence could result trapping of cortex behind the ring.

Next, he implanted a one-piece IOL, which he said he favored because its insertion is atraumatic relative to a three-piece implant. OVD was removed manually due to concern about the possibility of bringing vitreous forward using the I/A hand-piece in an automated technique.

Editorial from Peter McDonnell, MD: Giving weight to worrisome reports

“The outcome seemed favorable, although I felt if the lens decentered, I could still go back in the first few months postoperatively to suture the CTR to the sclera and avoid a more extensive secondary procedure in the operating room. Fortunately, the IOL has remained well-centered,” he said.

Ike Ahmed, MD

E: ike.ahmed@utoronto.ca

This article is based on a presentation given by Dr. Ahmed at American Academy of Ophthalmology meeting in 2015.

Dr. Ahmed is a consultant to Abbott Medical Optics, Alcon, and Bausch+Lomb.

Manual small incision cataract surgery (MSICS) does not make patients’ eyes any drier than phacoemulsification, a researcher said.

In two groups, one treated with MSICS and one with phacoemulsification, dry eye symptoms increased then declined to baseline in tandem after three months.

“The present study has shown that MSICS is as effective as phacoemulsification with no difference between both techniques as regarding effect on tear film stability and tear secretion,” wrote Mohamed Yasser Sayed Saif, assistant professor of ophthalmology, Beni-Suef University, Beni Suef, Egypt, and colleagues.

They published the finding in the International Journal of Ophthalmology and Eye Sciences.

Cataract accounts for much of the blindness in the developing world.

Phacoemulsification has become the standard of care in the developed world, but the density of cataract in many countries, along with the expensive equipment, makes it less feasible in the developing world, Dr. Saif and colleagues wrote.

Pioneering surgeons in India and Nepal have found ways to reduce the incision size and eliminate the need for sutures in manual cataract surgery, they noted. This approach mitigated the drawbacks of conventional extracapsular procedures: the need to remove sutures after three months and postoperative astigmatism, they wrote.

After the rapid development of alternative approaches, the first trials comparing MSICS with phacoemulsification began to show visual and vision-related quality of life outcomes nearly as good as those achieved with phacoemulsification, the researchers reported.

Comparing the procedures

Few studies have compared the effects of the two procedures on tear film stability and tear film secretion. Of those that have, they mostly focused on such subgroups as people with diabetes or preoperative dry eye.

Dr. Saif and his colleagues set out to compare the way the two procedures affected these outcomes.

They recruited 40 patients with a cataract and randomly assigned them to either phacoemulsification or MSICS. They excluded patients with diabetes, rheumatoid arthritis, and Sjögren’s syndrome.

In the phacoemulsification group, the mean age was 55.8 (± 15.8) years compared to 60.65 (± 9.2) years in the MSICS group. The phacoemulsification group was 90% female versus 45% in the MSICS group. The difference in age was not statistically significant, but the difference in gender was (P< 0.05).

Dry eye symptoms were characterized by burning, stinging, redness, sensation of a foreign body, photophobia, and blurred vision. They were graded as follows:

0: no dry eye symptoms.
0.5: trace or seldom of dry eye symptoms.
1: sometimes or mild dry eye symptoms.
2: frequent or moderate dry eye symptoms.

At baseline, none of the patients had a grade of 1 or 2. After one week, 80% of those in the phacoemulsification group and 90% of those in the MSICS group had a grade of 1 or 2. The difference compared to baseline within each group was significant, but the difference between groups was not.

After three months, 20% of those in the phacoemulsification group and 10% of those in the MSICS group had a grade of 1 or 2. The differences were not significantly different compared to baseline or between groups.

Looking at individual symptoms, the researchers found no significant differences between the two groups except for the presence of secretions three months after operation, which was significantly higher for the phacoemulsification group.

More conclusions

The researchers found no statistically significant difference between the groups in tear film breakup time either at baseline or any point of follow-up. In both groups, this measurement decreased a week after surgery, then increased after four weeks, nearly reaching baseline at three months.

The researchers also found no statistically significant difference between the groups in corneal fluorescein staining grade at any time point. One week after surgery, 55% of the phacoemulsification eyes and 45% of the MSICS eyes were stained grade 2, and after three months, the eyes had returned to baseline.

The groups also did not differ in Schirmer test. Both showed a decrease a week after surgery, and returned to baseline at three months.

The finding that dry eye symptoms increase for a week after surgery parallels previous research. Some of these studies found that the signs and symptoms persisted longer than three months after surgery, however.

The researchers acknowledged limitations to their study. One is that the same surgeon carried out both procedures, and it is possible the surgeon was more skilled at one than the other.

In addition, the sample size might not have been sufficient to detect small differences in outcomes between the two procedures. Finally, a longer term study might yield more definitive results.

Still, they concluded that the study showed MSICS does not affect tear film stability or tear secretion differently than phacoemulsification does.

“Because MSICS is significantly faster, less expensive, and less technology dependent than phacoemulsification, it may be a more appropriate technique in eyes with mature cataract in the developing world,” they concluded.

Reviewed by Jorge Alio

Take-home: Ocular surface disease, including dry eye disease, is common in patients undergoing cataract surgery. It must be treated in order to optimise the ocular surface prior to surgery, and close follow-up in the postoperative period is important.

Cataract surgery is one of the most-performed surgeries worldwide and patient expectations continue to rise as new developments and technology promise better outcomes. Ocular surface disease (OSD) in patients undergoing cataract surgery, which is often overlooked, plays an important role in determining the outcome of surgery and patient satisfaction.

(FIGURE 1) Meibomian gland capping and lid-margin telangiectasia in an asymptomatic patientThere is a high prevalence of dry eye disease (DED) in patients undergoing cataract surgery and studies have shown that 77% of patients have some corneal staining; however, 87% are asymptomatic.¹ Studies have also shown that 86% of patients presenting with dry eye symptoms suffer from meibomian gland dysfunction (MGD).²

Given that the incidence and severity of DED have been shown to increase after cataract surgery, it is extremely important to identify these patients and treat them appropriately.³ Cataract is also common in patients with immune-mediated OSD, because of their age and use of topical steroids, and following severe keratitis and corneal perforation.

Recognition and appropriate management of OSD reduces the risk of postoperative complications such as poor visual outcomes, delayed healing, infections, melts and visual loss.

Assessment

Surgeons should actively seek out signs and symptoms of OSD. A history of dry eye/mouth symptoms, collagen vascular disease and skin and joint problems may indicate the presence of OSD.

Fluctuating vision and an inability to read or watch television for prolonged periods are usually a sign of an unstable or insufficient tear film. It is useful to employ the Ocular Surface Disease Index grading to gauge the severity of disease and monitor progress prior to cataract surgery.⁴

Slit lamp assessment should include close inspection of the eyelid skin and margins. Rosacea, eczema, MGD, irregular and inflamed lid margins or tear film foam/debris may be present. Assessment of tears includes Schirmer’s test, tear meniscus height and tear film break-up time (TBUT). Wetting of ≤5 mm, tear meniscus height ≤0.2 mm and TBUT ≤5 seconds are highly suggestive of DED. Vital dye staining with fluorescein and/or lissamine green helps to quantify the extent of ocular surface damage.

These simple evaluations can be performed by all surgeons and may be complemented with measurement of tear osmolarity, detection of matrix metalloproteinases, lipid layer interferometry and keratography. These examinations, however, are expensive and are rarely performed as a preliminary to cataract surgery: they do have a role in other procedures such as refractive surgery.

Corneal topography and biometry may be inaccurate in patients with OSD and must be repeated after treatment with topical lubricants.

Management

The aim is to optimise the ocular surface prior to surgery, and patient education remains key in successful management. Patients may have presented with the preconceived idea that their symptoms are due to cataract. Treatment for OSD may therefore be regarded as unnecessary, meaning that they find the delay in their visual rehabilitation frustrating. Explaining its importance and the associated risks helps to improve compliance and manage expectations, which is particularly relevant if considering the use of premium IOLs. DED significantly affects patients’ perception of quality during the postoperative period.

Blepharitis is a common cause of DED and often a reason for cancellation of cataract surgery.⁵Hot eyelid compresses, lid hygiene, topical preservative-free lubricants and omega-3 supplements form the mainstay of treatment. Adjunct use of azithromycin, tetracyclines, short-term topical steroids or cyclosporine may be appropriate in patients with lid-margin inflammation and chronic symptoms.

A conjunctival swab and use of topical antibiotic ointment 7–10 days prior to surgery may also be advocated in patients with active ocular surface inflammation.

Ideally, the conjunctival inflammation in patients with immune-mediated OSD, for example mucus membrane pemphigoid, Stevens–Johnson syndrome or graft-versus-host disease, should be controlled in the months preceding surgery.⁶ In some cases, systemic immunosuppression in the perioperative period may be required. These patients should also be treated for concomitant lid-margin disease, and all patients with OSD should be advised to instil preservative-free topical lubricants. Punctal occlusion may also be considered but must be used with caution in patients with MGD.

Surgery

Preoperative medication should be carefully controlled and minimised.

Most cases can be treated effectively under local (topical and peribulbar) anaesthesia. Conjunctival manipulation must be kept to a minimum and sub-tenon anaesthesia and subconjunctival injections are best avoided. Eyelid retraction, symblepharon division and canthotomies may be required in some cases: general anaesthesia may be considered in such circumstances. Intraocular medication (1) may reduce the use of topical anaesthetics or mydriatics, which are highly toxic for the corneal epithelium.

Use of a cohesive ophthalmic viscosurgical device is useful to protect the corneal epithelium and maintain a good surgical view throughout surgery. In cases with a compromised surgical view, changing microscope illumination, using trypan blue for capsular staining or endoillumination may help improve visualisation.

Postoperative care

As DED may worsen following surgery, it is of paramount importance to maintain close follow-up in the postoperative period. Preservative-free steroids, antibiotics and lubricants should be considered following surgery in all patients with DED. Topical cyclosporine is effective in managing OSD and improving corneal sensation after cataract surgery and may be considered if not prescribed preoperatively.⁷

^{(FIGURE 2) a) Non-healing epithelial defect and corneal staining following cataract surgery b) Healed epithelium following treatment with intensive lubricants, punctal occlusion and autologous blood.}

It is important to identify any epithelial defects and grade the conjunctival inflammation in the postoperative period. Non-healing corneal epithelial defects may lead to melts, infection, perforations and sight loss. Aggressive systemic and local therapy may be required, including use of amniotic membrane, autologous blood and induction of ptosis.

Conclusions

OSD is highly prevalent in patients undergoing cataract surgery; surgeons must actively seek its signs and treat aggressively. In asymptomatic patients, this is key in producing the successful refractive outcomes that they expect. In those with established OSD, it will also aid maintenance of vision and avoid permanent visual loss.

References

References

W. Trattler et al., Poster, American Society of Cataract and Refractive Surgery Annual Symposium and Congress. San Diego; March 2011.
M.A. Lemp et al., Cornea 2012; 31(5): 472-428.
Y.K. Cho and M.S. Kim. Korean J. Ophthalmol. 2009; 23: 65-73.
R.M. Schiffman et al., Arch. Ophthalmol. 2000; 118: 615-621.
R.E. Stead et al.,Eye (Lond). 2010; 24(4): 742.
V.P. Saw and J.K. Dart. Ocul. Surf. 2008; 6(3): 128-142.
S. Hamada et al.,Cont. Lens Anterior Eye 2016; 39(1): 15-19.
B. MiljanoviÄ et al., Am. J. Ophthalmol. 2007; 143: 409-415.
S.E. Moss, R. Klein and B.E.K. Klein. Arch. Ophthalmol. 2000; 118: 1264-1268.
K.E. Han et al., Am. J. Ophthalmol. 2014; 157: 1144-1150.
M.Q. Salomão, R. Ambrósio Jr. and S.E. Wilson. J. Cataract Refract. Surg. 2009; 35: 1756-1760.

12 N. Kasetsuwan et al., PLoS One. 2013; 8: e78657.

13. J.L. Rodriguez-Prats et al.,J. Refract. Surg. 2007; 23: 559-562.

14. Labetoulle M, Findl O, Malecaze F, Alió J, Cochener B, Lobo C, Lazreg S, Hartani D, Colin J, Tassignon MJ, Behndig A; Intracameral Mydrane Study 2 Group.Evaluation of the efficacy and safety of a standardised intracameral combination of mydriatics and anaesthetics for cataract surgery.Br J Ophthalmol. 2015 Nov 3. pii: bjophthalmol-2015-307587

Amit Patel is consultant ophthalmologist at Spire Parkway Hospital in Solihull, West Midlands.

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Reviewed by Johan Blanckaert

Take-home: The Allegro I/A tip system comprises a preassembled, single-use silicone I/A tip, which has advantages over other commercially available products. It helps to reduce capsular rupture during cataract surgery and also eliminates tricky tip assembly and cleaning.

During phacoemulsification, it is necessary to aspirate material and supply irrigation fluid. Unfortunately, some irrigation/aspiration (I/A) devices may cause posterior capsular rupture. Surgical technique is key in preventing capsular rupture: for example, it is possible to reduce the risk of a posterior capsular tear by positioning and maintaining the I/A tip anterior, rather than posterior, to the IOL.¹

Evidence suggests that the material from which the I/A tip is made can also be important. Interestingly, research published more than 30 years ago reported a case of posterior capsular rupture following the use of a new hard I/A tip. Using scanning electron microscopy of the tip, the authors observed burrs on the aspiration portion of the tip as well as poor finishing around the irrigation ports.²

A study undertaken at the University of Texas Southwestern Medical Center, Dallas, USA showed that use of a silicone I/A tip reduces the risk of capsule rupture.³ The study found that the overall incidence of vitreous loss during cortex removal was significantly decreased using a silicone- rather than a metal-tipped I/A instrument. Of the 1072 cases that used a metal tip, 13 (1.2%) experienced vitreous loss during cortex removal; 26% of all vitreous loss occurred during cortex removal. Of the 805 cases that used a silicone tip, there was only a single case (0.1%) of vitreous loss during cortex removal (p=0.004) and only 4% of all vitreous loss occurred during cortex removal (p=0.011).³

A preassembled silicone I/A system

A preassembled silicone I/A system

There are a number of silicone I/A tip systems now available. Some are reusable, some disposable and some a combination of both. I use the Allegro I/A silicone-encapsulated tips in conjunction with the Allegro handpiece (MicroSurgical Technology, Inc., Redmond, WA, USA). While the handpiece is designed to be reusable, the tips are for single use.

The Allegro I/A tip system has several advantages over other systems. Not only is it capsule friendly, the tip comes preassembled, thus eliminating the need to fit a sleeve. Two bends in the tip provide improved access to the subincisional cortex with less torque on the wound, while the irrigation port is optimised for working close to the wound. The Allegro I/A tip also permits easy IOL rotation.

(FIGURE 1)

My experience

My experience

There are a number of reasons why I use the Allegro I/A tip system. First, I wanted to use something soft, rather than hard metal, to avoid wear and small burrs at the tip, which can rupture the posterior capsule. The second advantage for me is the fact that the tip comes preassembled, which saves time and errors in assembly. Reusable silicone tips exist but are notoriously difficult to clean, with cortex particles, which can pass to the next patient, being retained in the tip. I am uncomfortable with this and prefer a single-use system.

Another point is that the Allegro I/A tip system is good for all cases, including standard and femtosecond-laser cataract surgery. Some doctors are a little intimidated by femtosecond-laser cases because the cortex is cut at the same level as the anterior capsule: they have to reach further in order to get the cortex. This can be difficult with some tips, but the Allegro has just the right amount of curve. Also, if there is a piece of cortex stuck to the posterior capsule, it is possible to use the silicone tip to peel it off. You might see the capsule wrinkle a little, but it won’t tear.

The only downside to the Allegro is that it is designed to be used with an incision of 2.2 to 2.4 mm: with a larger incision, there tends to be a little egress of fluid. However, I believe that MicroSurgical Technology is developing a larger tip for surgeons who use incisions greater than 2.4 mm. Overall, this system has solved most of the problems we have had with previous tips, which is why I use the Allegro I/A tip system for around 80% of my cataract procedures.

References

References

1. B.W. Sim et al., Clin. Experiment. Ophthalmol. 2013; 41(5): 450-454.

2. C. Reed-Miller, K.B. Heslin and S. Liebowitz. J. Am. Intraocul. Implant. Soc. 1985; 11(4): 391-392.

3. P.H. Blomquist and A.C. Pluenneke. J. Cataract Refract. Surg. 2005; 31(6): 1194-1197.

Dr Keith Walter

E: kwalter@wakehealth.edu

Keith Walter, MD, is a professor of ophthalmology at Wake Forest Baptist Medical Center, North Carolina. Professor Walter has no financial interests in MicroSurgical Technology, Inc.

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Boston–Cataract surgery in the post-vitrectomized eye is considerably tricky but with some surgical experience and implementing some valuable pearls—including whether to hydrodissect or hydrodelineate—surgeons can avoid surprises, according to Bonnie An Henderson, MD.

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“First, ensure you are not hydro-dissecting these eyes, but hydro-delineating,” said Dr. Henderson, partner at Ophthalmic Consultants of Boston and clinical professor at Tufts University, Boston. “The telltale sign of a successful hydrodelineation is the ‘golden ring.’ Be aware these lenses are unlikely to rotate well, so carefully proceed with chopping and removing the fragments to debulk the nucleus.”

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Dr. Henderson presented this case during a panel discussion on cataract complications at the 2015 meeting of the American Academy of Ophthalmology.

When performing such surgeries, Dr. Henderson prefers to move her phaco tip “to get to the different areas of the bisected nucleus and then try to segment them into smaller pie pieces,” rather than attempting to rotate the entire lens and keeping the phaco tip in the center.

Patience is required

Patience is required

She added that surgeons need patience, and be even more meticulous than normal in vacuum and removal. Once the epinuclear shell is the only object left, removal will be trickier with hydrodissection, but necessary.

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“I try to maneuver my phaco by rotating the face of the opening to try to occlude the tip against the nuclear fragment,” Dr. Henderson said.

When the epi-nuclear shell is difficult to mobilize, she uses a second instrument, like a chopper, to assist in the removal. But, when hydrodissection is not performed, there may not be an obvious “good plane to insert the chopper.”

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The options with an adherent epi-nucleus are to hydro- or viscodissect, switch to bimanual irrigation and aspiration (I/A) without hydrodissection, or create a new incision for a coaxial I/A. If the surgeon is suspicious of a posterior capsule breach, further hydrodissection is not a good option.

Zonules also can be compromised, and surgeons “should always assume there’s going to be a problem in patients post-vitrectomy,” added panelist Alan Crandall, MD, senior vice chairman and clinical professor of ophthalmology and visual sciences, University of Utah, Salt Lake City.

He recommended that surgeons obtain an ultrasound biomicroscopy to make sure the posterior capsule is in tact.

“Particularly when the nucleus is dense enough you cannot see anything,” he said.

The question remains whether a dispersive or cohesive viscosurgical device (OVD) would be preferred. To maintain the space without a quick egress of the OVD during manipulation, a dispersive may be best. However, to viscodissect behind the lens initially with easy removal afterward, a cohesive is best.

Dr. Henderson, however, noted that in order for the case to be successful, other variables need consideration. In this case, because the incision construction was not ideal as tri- or bi-planar, she encountered an iris prolapse.

“Fortunately, the iris stayed dilated even with the prolapse,” Dr. Henderson said.

Posterior capsule intact

Posterior capsule intact

After the lens nucleus was removed, the posterior capsule appeared intact. Dr. Henderson proceeded to remove the epinucleus, but it remained stuck.

She attempted a hydrodissection and at that point, the posterior capsule ruptured, she said. She carefully injected OVD to stabilize the eye before removing the phaco tip.

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“The good news is there’s no vitreous coming forward in post-vitrectomy eyes,” she said. “But the bad news is that there’s no support.”

Dr. Henderson used a chondroitin sulfate OVD to inject underneath the fragment and elevate it with a cannula. She then used a vitrector to clean up any residual cortical material that is warranted even in post-vitrectomy eyes.

In eyes like these, “if there is a rapid onset cataract, you have to be worried,” Dr. Henderson explained. “Look at the formation of the cataract. If the posterior aspect of the cataract is irregular, it is possible that there is a weakening of the posterior capsule. Always skip the hydrodissection; even after the nucleus is removed it is probably best not to hydrodissect with balanced salt solution.”

Finally, after the cataract surgery is complete and if there is retained nucleus, the cataract surgeon and referring retina specialist should work in unison to determine the best follow-up plan. Follow-up should be a few weeks after the surgery.

Surgeons might also consider using steroids for a few weeks to control the inflammation. If the epinucleus fragment is large, it may cause patients visual disturbances or floaters that would warrant an earlier removal, the panelists added.

Dr. Crandall pointed out that intraoperatively, staining could help since it is variable how the eye will react. If surgeons opt to hydrodissect, it is “highly recommended” to proceed slowly and hydrodelineate if necessary. He added that using a low-flow pattern so the surgical occlusion will not pop the bag is another little trick.

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Bonnie An Henderson, MD

P: 781/487-2200

E: BAHenderson@eyeboston.com

Dr. Henderson is a consultant to Abbott Medical Optics, Alcon Laboratories, Bausch + Lomb, ClarVista, Regeneron Pharmaceuticals, and Stealth. She also holds a patent with Massachusetts Eye and Ear Infirmary.

Las Vegas—It is anticipated more than 3.7 million cataract surgeries were performed in the United States in 2015, 98% of them by means of phacoemulsification.

“Of the additional 20.3 million cataracts done in other countries, 64% of them (were) by phacoemulsification,” said Warren Hill, MD. “I can think of very few technologies in our field that have this kind of longevity, and the life of Dr. (Charles) Kelman is a wonderful example of what is possible when we think ‘different.’ ”

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Dr. Hill, in private practice at East Valley Ophthalmology, Mesa, AZ, presented the Charles D. Kelman Lecture entitled, “IOL Power Selection: Think Different” at the 2015 meeting of the American Academy of Ophthalmology.

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While the accuracy of IOL power selection has advanced since the early days of phacoemulsification, the selection of the proper IOL power is always in the background when a surgeon performs cataract surgery, Dr. Hill said.

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He added that the continued emphasis on improving outcomes is to increase patient safety and reduce the many burdens associated with a refractive surprise.

“If a patient ends up -4D, it’s an annoyance for us, but (it) can be a life-changing event for the patient,” Dr. Hill said.

Improving calculations

Improving calculations

Even with the most advanced metrics and the use of multiple theoretical formulas, there can still be problems with the selection of IOL power, Dr. Hill pointed out.

The simple fact is that surgeons don’t get the IOL calculations right all the time. Refractive targets within 1 D are usually achieved, but the discrepancy between what was expected and what is reached for a ±0.50 D accuracy remains problematic.

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For more than a decade, Dr. Hill has reviewed physician databases for lens constant optimization from surgeons around the world, totaling more than 260,000 optical biometry cases.

Each physician submits between 200 and 300 cases, which typically represents their best work.

What Dr. Hill has found is that fewer than 1% of surgeons have a refractive accuracy of 92% or better within ±0.5 D.

“Six percent reach that level of accuracy 84% of the time, and the vast majority reach that level of accuracy only 78% of the time,” Dr. Hill said. “If we’re in the business of putting in lens-based refractive IOLs, this is probably not good enough.”

The “mathematical backbone” of all theoretical formulas is basically the same: Lens vergence equals image vergence minus object vergence.

“The recurring difficulty with this approach is the power of the IOL inside the eye is relative and not absolute,” Dr. Hill said. “Inside the eye, a 21 D lens only acts as a 21 D lens a certain distance from the cornea.”

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Place it a bit more anterior or posterior and the lens will have a different relative power. That distance is commonly referred to as the “effective lens position” (ELP) of an IOL. This represents the “significant part” of the accuracy of any theoretical formula calculations.

“Theoretical formulas have to first estimate the position of the IOL inside the eye before performing the rest of the calculation,” Dr. Hill added. “And with regrets, the effective lens position is an unknowable quantity—something that can only be estimated and not directly measured.”

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So, ophthalmologists are faced with the problem that preoperative measurements and the actual postoperative ELP are not always correlated. Using that same 21 D example, “a 0.5-mm mis-estimation of the ELP is a 1 D error at the plane of the capsular bag.”

“Try holding your fingers 0.50 mm apart and it’s easy to see how sensitive all of this can be,” Dr. Hill pointed out. “The ELP remains a major limiting factor for all theoretical formulas.”

Changing calculations

Changing calculations

Almost 20 years ago, Gerald Clarke, MD, an ophthalmologist in Wisconsin, showed that by using a completely different approach for IOL power selection, the accuracy could be improved by more than 80% over a conventional theoretical formula of the day–and this was before optical biometry and sophisticated keratometry were introduced, Dr. Hill said.

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“But we in ophthalmology overlooked this,” Dr. Hill explained. “That paper should have been a wake-up call, but it did not gain the attention it should have. Like many good ideas, looking back it was a wonderful idea, but way ahead of its time.”

However, Dr. Clark’s insights did lay the groundwork for a closer look at the concept of adaptive learning, by which a method for IOL power selection can be developed that is based solely on data and independent of what was previously known, Dr. Hill explained.

“Such a method is well suited to the task of pattern recognition and complex nonlinear relationships,” he added.

With the sophisticated mathematical tools currently available, surgeons have the ability to think about lens calculations “as a pattern,” Dr. Hill said. “For any axial length, anterior chamber depth, central corneal power and IOL power producing a given post-operative spherical equivalent, we can approach this as a pattern.”

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Dr. Hill showed an example in which 1,000 seemingly random points were placed within a box, although these points were not actually random, but were created using a “Manhattan distance” generator. In layman’s terms, imagine the city blocks of Manhattan as little squares.

Feature extraction

Using a concept of feature extraction and feature matching, Dr. Hill showed how a neural network was able to begin with “a seemingly chaotic collection of points and demonstrate that it actually has a pattern. The neural network was able to establish this and create a self-organizing map,” Dr. Hill said.

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Improvement upon the original neural network concept from the 1940s is a different mathematical model known as a radial basis function. Dr. Hill said it handles nonlinear relationships and it “does the best with the fewest amount of necessary inputs, which means it thinks for itself. And for the task of IOL power selection, this sophisticated form of data interpretation becomes an enormously powerful tool.”

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While the terminology is novel for most ophthalmologists, the use of the radial basis function model is not. It is used for fingerprint recognition, in the automotive industry to calibrate engines, in facial recognition software by law enforcement agencies, and for EKG interpretation.

Dr. Hill, his team of physician investigators, and the mathematicians and engineers at MathWorks developed a study protocol to evaluate the data to determine the best measurement parameters (factors) to be used. Axial length, central corneal power, and anterior chamber depth were deemed the most important factors.

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“Developing this, we didn’t want to have something encumbered by too much data,” Dr. Hill said. “In this case, the more variables we used, the less accurate the IOL power selection method became.”

The new paradigm

The new paradigm

Realizing all formulas have limitations, “the difference between conventional formulas and RBF pattern recognition is that there is no calculation bias,” Dr. Hill explained. “The RBF method does not know that a 21-mm eye is very short or that a 28-mm eye is very long eye. All it knows is a pattern of data produces a particular result.”

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This new IOL power selection method also incorporates a feature commonly employed in engineering, but new to ophthalmology, known as a “boundary model.”

One of the more powerful features of pattern recognition, based in artificial intelligence, is that the limits, or “boundary,” of calculation accuracy can be identified. Within such a boundary, surgeons can anticipate a predicted accuracy and outside of which they may not have enough data to for accurate interpolation.

When using the RBF calculator, an IOL power is identified as being “In Bounds,” or “Out of Bounds.” The implications of this added level of security are significant and are meant to enhance patient safety and physician confidence. With conventional theoretical formulas, data is entered and the user hopes for the best.

The RBF model is a “big data” exercise, Dr. Hill explained. When the dataset used to fit the RBF model was expanded from 681 cases to 3,445 Lenstar cases, the depth of calculation accuracy dramatically improved. For the boundary model of axial length versus ACD, across an enormous range of values, the RBF model was unable to resolve the question in only 12 cases.

Retrospective testing

For retrospective testing, looking at 3,212 independent cases from 13 surgeons in eight countries, the outcomes have been impressive with a weighted mean ±0.50 D accuracy of 95%.

“No one’s ever seen numbers like this,” Dr. Hill said.

What is even more impressive than the accuracy is the consistency from one beta test site to the next across Europe, the Middle East, Africa, North and South America, Asia, India, and Australia. This level of consistency reveals that the outcomes are technologically driven.

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“In summary, this is a new approach based on pattern-recognition, data interpolation, and a validating boundary model, but just adds an additional level of confidence, and the accuracy of this methodology is due to an increase in flexibility,” Dr. Hill said. “The RBF calculation method will soon be incorporated into the Haag-Streit Lenstar EyeSuite software.”

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A free, web-based, online version of this calculator is expected to be functional on the American Society of Cataract and Refractive Surgery website and at RBFCalculator.com by April or May 2016.

Warren Hill, MD

E: hill@doctor-hill.com.

Dr. Hill is a consultant for Alcon Laboratories and Haag-Streit.

Take-home message: An IOL calculator must take into consideration the various challenges cataract surgeons face when making an IOL selection and be easily accessible.

By Vanessa Caceres; Reviewed by Samir I. Sayegh, MD, PhD, FACS

Champaign, IL—Cataract surgeons can use IOL calculators to help achieve the best possible surgical outcomes and spend less time calculating the right IOL choice, said Samir I. Sayegh, MD, PhD, FACS, The Eye Center, Champaign, IL.

Some challenges that cataract surgeons face during the IOL selection process is calculating sphere, obtaining biometric data from multiple devices, and figuring out what other factors to include, such as multiple Ks, posterior astigmatism, and anterior chamber depth, Dr. Sayegh said.

Yet other challenges that cataract surgeons grapple with include toric-related issues, such as using a fixed or variable “toricity ratio” and the sometimes-bewildering variety of IOLs and manufacturers.

One tool that can help cataract surgeons is a universal, yet customized, IOL calculator, Dr. Sayegh said.

Such a calculator would need to include several features, he explained.

What surgeons need to know

These include multiple approaches such as well-tested and openly published formulae (for instance, SRK/T, HofferQ, and Haigis), multiple toric computation paradigms (including fixed and variable toricity ratios), access to an extensive database of IOLs but also allow for a surgeon’s customization, and multiple ranking preferences that minimize sphere error or astigmatism first—or, more global criteria that optimize sphere and cylinder residuals simultaneously.

Such a calculator would need to be Internet-accessible and easy to access online, be it on a computer, mobile device, or phone, Dr. Sayegh said.

The core calculator would need to include IOL power, toric options, ranking, and preferences. The lens database that is part of the system would need to include options from the variety of manufacturers and provide monofocal, aspheric, toric, and multifocal choices.

Dr. Sayegh has designed UniversIOL, an IOL calculator that helps meet the challenges outlined.

He said his calculator is extensive and has a growing universal database of IOL types and IOLs. The calculator also provides a choice of formulae for sphere and toric computation, a choice of computational strategies, and a choice of IOL-ranking criteria that is selectable by each surgeon.

Dr. Sayegh’s calculator, called UniversIOL, is available at https://www.universiol.com. A demo can be accessed at http://2020eyecenter.com/iol-calculator/.

Samir I. Sayegh, MD, PhD, FACS

E: sayegh@umich.edu

Dr. Sayegh has no financial interest in the subject matter.

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