EyeWorld Asia-Pacific December 2015 Issue

11 December 2015 EWAP FEATURE concept but I think personally that the reason you get a burn in high- density viscoelastic is you don’t establish flow,” Dr. Barrett said. “Once you establish flow, I think the exothermic property is probably not the most important.” “Is chilled BSS a solution in the prevention of wound burn?” Dr. Bellucci asked. “We didn’t look at that specifically,” Dr. Chan said. “But like Graham said, I think really it’s a flow issue, not so much the actual temperature, because once you get that energy rise, there’s going to be heat generated and it’s actually the friction as well. So does it help? It probably does no harm, but just how much benefit, I’m not so sure.” Eccentric pupils “When you have an eccentric pupil, you really need to pay attention to it for several reasons,” Dr. Barrett said. “If you don’t deal with that issue, patients will have visual dysfunction; they’ll have glare, possible photophobia; their visual acuity and contrast will be reduced; and there’s also cosmetic issues.” The eccentric pupil also presents challenges from a surgical standpoint. One is simple access: if the pupil is eccentric, possibly attached with synechia, access to the cataract may be impeded. In addition, eccentric pupil may also be associated with other defects such as zonular dialysis. For purposes of discussing the principles of management, Dr. Barrett classified eccentric pupils into congenital, traumatic, secondary to associated conditions such as dialysis or adhesion, and iatrogenic. One of the most common causes of eccentric pupil are congenital colobomas. “Always be cautious with a coloboma that may not be associated with dialysis—a lens coloboma as well as the iris coloboma,” Dr. Barrett said. “One of the temptations when you have a coloboma of the iris and you have an irregular pupil is to try and restore that pupil to normality simply by suturing that defect,” he said. “That may not be the best approach because you simply drag the centricity even further away from the center of the cornea.” Instead, Dr. Barrett prefers a sector iris prosthesis. “Rather than trying to close the gap in the defect, I use an occluder,” he said. “There’s various different sizes, different sizes of iris diaphragm, and by choosing one that’s appropriate, once that’s inserted in the capsular bag, you can rotate it, cover the defect, and definitely the patient’s visual function does improve in that circumstance.” The next most common group of eccentric pupils encountered, Dr. Barrett said, are those subsequent to trauma, particularly with an iris dialysis. In these cases, he said that the pupil would actually be decentered in the opposite direction from the dialysis. In one case with a dense cataract and scarred capsule that required vision blue for visualization and to access the pupil, Dr. Barrett’s biggest challenge was performing the rhexis. In this case, Dr. Barrett used 25-gauge scissors to bypass the scar. Dr. Barrett was able to create a smooth, intact-looking rhexis using the scissors, but the scar remained a weak point for the capsule. Great care was needed to avoid causing that weak point to tear and extend. Dr. Barrett proceeded to use a vertical chop technique. He removed the dense nucleus and inserted a lens into the capsular bag. “It almost looks that my rhexis is actually intact,” Dr. Barrett said. “Certainly it’s more than adequate to hold this lens securely in place and the lens is well centered. But we need to deal with the dialysis.” The dialysis, he said, is a defect that can let a little light through and affect vision. In addition, leaving the defect leaves the pupil off center. Repairing the dialysis—in this case using one or two 10-0 prolene sutures—closes the defect and brings the pupil back to center. In his next case, Dr. Barrett dealt with adhesions. Access was difficult because the pupil was stuck to a scar. In such a case, Dr. Barrett prefers iris hooks over pupil expansion rings. With hooks, he said, “I can always titrate how many hooks I need. Particularly with a scarred, stuck-down pupil, I found that was more helpful.” Also helpful—essential, in fact, according to Dr. Barrett— in managing complex cataract surgery was dual linear control. “I can titrate just the amount of energy required and the amount of vacuum required,” he said. “Particularly when you don’t have full visualization, this gives you really superb control of your ocular environment.” The eccentric pupil can present another challenge to surgeons: access to the space behind the lens in order to remove viscoelastic may be difficult. However, for Dr. Barrett, this is not a problem. “I never go behind the lens to remove the viscoelastic,” he said. “If you simply stay in front of the lens, push it back against the capsule, aspirate the viscoelastic, there really is no need to put the aspiration behind the lens.” With the pupil stuck to the iris, it was tempting to remove the adhesions. However, in this particular case, the adhesions were actually protecting the visual axis from the central corneal scar. Dr. Barrett thus elected to leave the pupil as it was, and achieved good visual outcomes. Finally, Dr. Barrett managed an iatrogenically eccentric pupil. The patient had congenital glaucoma and had undergone iridoclysis. The glaucoma was controlled, but the pupil was “not in good shape.” The “good eye” had had an optical iridectomy performed; the bad eye—the hand-movements eye—had a very dense, brunescent cataract, was buphthalmic, with a break in Descemet’s membrane and endothelial decompensation. “You normally wouldn’t operate on an eye like this…everyone had told [the patient] not to touch this eye, there was no use,” Dr. Barrett said. “But he wanted to try and see what could be obtained before we touched his only good eye… because this was the patient’s wish, I decided to operate on the eye.” Dr. Barrett once again used hooks to gain access. “I still like hooks,” he said. “They take a bit longer to put in than the rings, but sometimes you need continued on page 12