EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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34 EW FEATURE February 2011 Cataract challenges July 2013 Big lessons for small pupil cataract surgery by Maxine Lipner EyeWorld Senior Contributing Writer AT A GLANCE • Use of the more tissue-friendly Malyugin ring is one mechanical way surgeons can contend with small pupils in traditional and IFIS cases. • New study results show that use of intracameral phenylephrine 1.5% is effective for both preventing and reversing IFIS and accompanying pupil constriction. • Off-label use of the femtosecond laser is gaining ground in small pupil cataract cases, together with the Malyugin ring and dilating solutions. Getting educated on the latest approaches F or patients who have small pupils or who develop them during cataract removal, current innovations are making the surgery as uneventful as possible. Solutions range from use of Malyugin rings (Microsurgical Technology, MST, Redmond, Wash.) and other pupilexpansion devices to pharmacological phenylephrine dilation to fetlocked laser use and more. Having a small pupil to contend with during cataract surgery is no minor issue, according to Boris E. Malyugin, MD, deputy director general, S.N. Fyodorov Eye Microsurgery Complex, Moscow. "The small pupil, apart from the obviously increased chances of iris damage, gives poor visualization because you don't have good access to the lens," Dr. Malyugin said. "And there is a tendency to create a smaller capsulorhexis." This can cause greater propensity toward the risk of anterior capsule damage with the ultrasonic needle, the chopper, or another instrument used during the phacoemulsification process. It can result in more difficult evacuation of the cortical material because of visualization issues, he explained, adding that it can also lead to difficulty in ensuring the lens is correctly implanted and potentially enhances the chance of capsular phimosis postoperatively. The Malyugin ring sounds the first bell To make visualization easier, Dr. Malyugin pioneered his now oftused ring several years ago. He felt that the need was unfulfilled at that point. "It was a demand (from) some unmet expectations because even though using pharmacological agents is very effective, in many cases this approach is not sufficient," Dr. Malyugin said. Likewise, prior mechanical approaches were less than optimal. "Cutting the iris is quite a wellknown and well-established technique," Dr. Malyugin said. "I was concerned with bleeding because there is a high chance of this when you are cutting the highly vascularized iris tissue." He wanted an option that was potentially more forgiving to tissue than traditional stretching methods. With the Malyugin ring, the expanded pupil is round—despite the fact that the device has a square edge. "In spite of the device being square, the pupil is round because the corners of the device are connected with the thread that supports the iris and catches it in the middle of the side portion of the ring," Dr. Malyugin said. This method of expansion is less traumatizing to the tissue than iris hooks, which result in a square stretched pupil, with a perimeter that is longer in places than with the Malyugin ring. "With the Malyugin ring the iris tissue is not overstretched," Dr. Malyugin said. The ring comes in two diameters—6.25 and 7 mm. The larger ring was created especially for intraoperative floppy iris (IFIS) cases, he noted. "The pupil can actually be bigger at the beginning of an IFIS case, then during the procedure it starts to constrict," Dr. Malyugin said. If the physician suspects the patient may develop IFIS and attempts to prophylactically insert the ring before pupil constriction begins, the bigger ring is needed, he explained. William W. Culbertson, MD, professor of ophthalmology; director of cornea and refractive surgery services; and the Lou Higgins Chair of Ophthalmology, Bascom Palmer Eye Institute, Miami, finds the Malyugin ring preferable to traditional iris hooks for typical small pupil cataract cases. Such hooks are good if a large 3 mm incision isn't otherwise required. "When you've already got a cataract incision I think the Malyugin ring is very good," Dr. Culbertson said. For preventing pupils from constricting during an IFIS cataract case, he thinks the ring is extremely effective. "It raises the cost of the case in the $100 range, but it's easy to put in and easy to remove," Dr. Culbertson said. "It gives you 7 mm of viewable area, which is quite adequate." During the IFIS case it stabilizes the pupil in the right position and prevents it from flopping, he said. Studying up on pharmacology Dilating drops have a role in cataract cases involving small pupils. If the pupil constricts during the case, it may be that the patient received inadequate dilating drops initially or that it has been too long since the patient received drops. In such cases, practitioners can use intraocular solutions to expand the pupil, Dr. Culbertson said. Bisulfate-free epinephrine is one possibility. The other is intraocular lidocaine, dubbed Shugarcaine after deceased practitioner Joel Shugar, MD. It's possible to use these together in another solution, epi-Shugarcaine. "The lidocaine can cause the pupil to dilate, paralyzing the pupil sphincter, and the epinephrine stimulates the pupil dilator," Dr. Culbertson said. One recent approach is to inject phenylephrine 1.5%. This is something that must be compounded in the United States, Dr. Culbertson said. It can be combined with lidocaine. At the Bascom Palmer center, where there is a compounding pharmacy on the premise, this has been dubbed Bascom Palmer-caine. "It seems to be very effective in preventing pupil constriction, and it makes the iris less floppy in IFIS," Dr. Culbertson said. In traditional small pupil cases, where visualization is inadequate from the start, after topical dilation has been tried, pharmacological methods may not do the trick, said Ramon Lorente, MD, chairman, Department of Ophthalmology, Complexo Hospitalario Universitario Ourense, Spain. "In our experience, pharmacological methods such as intracameral adrenaline or phenyle- phrine are not effective as they do not increase the previous topical dilation," Dr. Lorente said. The new 'book' on IFIS For IFIS cases, however, it may be a different story. Dr. Lorente and fellow investigator Victoria de Rojas, MD, chairman, Department of Ophthalmology, Complexo Hospitalario Universitario A, Couruna, Spain, together with others, recently considered how prophylactic administration of intracameral phenylephrine (IPH) would affect the development of IFIS. "After prospectively reviewing the efficacy of this approach in a large series of patients at risk of IFIS, starting in 2007, we decided to evaluate the efficacy of IPH 1.5% as prophylaxis against tamsulosinassociated IFIS," Dr. Lorente said. The study, published in the October 2012 issue of Ophthalmology, also analyzed the ability of the phenylephrine to reverse the floppy iris syndrome. During the study, signs of IFIS were observed in 88.09% of eyes that were randomized to receive balanced salt solution. However, no signs of IFIS were seen in eyes that received 0.6 ml of non-preserved bisulfite-free IPH 1.5%. Significant pupil constriction, iris prolapse, or both occurred in 54.76% of the balanced salt solution eyes, Dr. Lorente reported. "However, the condition was successfully reversed with IPH, with a significant increase in pupil size after IPH administration," Dr. Lorente said. He was encouraged by the results. "Our study clearly showed that intracameral phenylephrine is a highly efficient measure for prophylaxis against IFIS," he said. "Moreover, the drug can reverse IFIS, restoring iris rigidity and causing the pupil to return to its preoperative size." Currently, Dr. Lorente is now dilating patients at risk of IFIS directly with intracameral phenylephrine 1.5% together with lidocaine 2%. This, he finds, avoids the need for topical instillation of dilating drops, with good results. "The dilated pupil size is slightly smaller than that obtained after topical mydriatics, but it lasts longer and it avoids systemic absorption with its possible cardiovascular adverse effects," he said.