EyeWorld Asia-Pacific December 2014 Issue

December 2014 9 EWAP FEATURE Views from Asia-Paci c CHEE Soon Phaik, MD Senior Consultant, Head of Department Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 Tel. no. +65-6227-7255 Fax no. +65-6227-7290 chee.soon.phaik@snec.com.sg A s highlighted by the three expert discussants, pseudoexfoliation syndrome eyes are associated with zonular weakness, poor pupil dilation and glaucoma. Having a combination of the former two risk factors can make cataract surgery challenging, especially when the nucleus is often harder than it appears on slit-lamp examination. Patients should be counseled that they may require insertion/ xation of a capsular device, even if the cataract appears stable preoperatively. An ultrasound biomicroscope examination can detect absence or weakness of zonules and is useful for planning surgery. In addition, endothelial cell count should be done when the nucleus is dense. If the pupil dilates reasonably, I prefer a femtosecond laser capsulotomy which is performed without stressing the zonules. The laser fragments the nucleus, minimizing ultrasound energy and reducing surgical maneuvers that stress the zonules. I also prefer using iris hooks for a small pupil which can double up to support the capsular bag if the lens is unstable (for example with dif culty puncturing the anterior capsule, anterior capsule folds during capsulorhexis, pseudoelasticity). A capsule tension device is used if there is any hint of zonulopathy and the ring is inserted immediately after anterior capsule removal. To avoid entrapment of cortex, viscoelastic is injected just under the anterior capsule and the cortex-free plane is expanded to facilitate insertion of the device. Depending on the severity of zonulysis, which may increase during cataract surgery, capsular tension segments may be added to support the bag without further stressing existing zonules by avoiding in-the-bag rotation. Iris hooks are used to support the bag by latching onto the eyelets during surgery. If insertion of CTR or hooks is delayed, posterior misdirection of uid develops, increasing the risk of posterior capsule rupture. I place a CTR if zonular weakness exists to prevent capsular phimosis because of unopposed capsular bag brosis which contributes to late IOL subluxation. If there is any zonular dehiscence observed during surgery, I xate the capsular bag/IOL complex because this is a progressive zonulysis. I generally favor a single-piece IOL which is gentle on the zonules. If the capsular bag/IOL subsequently subluxates, I dissect open the bag and add one or two capsular tension devices. I routinely use Hoffman sclerocorneal pockets for xation, which spares the conjunctiva—especially important for glaucoma eyes. As highlighted, the ophthalmologist should be on the lookout for late IOL dislocation. Symptoms include blurring, seeing a crescent (displaced anterior capsule of the capsular bag) or they may present with low-grade in ammation due to intermittent chaf ng of the mobile IOL/bag against the iris. Editors’ note: Prof. Chee is a consultant for Abbott Medical Optics and Bausch + Lomb and receives travel support and an honorarium. “Avoid overfilling the eye with viscoelastic, as excessive deepening of the anterior chamber can place undue stress on the zonules,” Dr. Gedde said. To prevent the mechanical stress of phaco from being transferred to the capsule or the zonules, Dr. Hart recommends fully hydrodissecting the lens so that it is spinning freely inside the capsule and using a chopping technique rather than divide-and- conquer. During cortex removal, Dr. Giaconi recommends stripping the cortex tangentially toward the area of weakness, rather than away from it, which will tear more zonules. Patients with zonular dialyses are also at risk for posterior fluid misdirection, said Dr. Gedde, which increases vitreous pressure and decreases the depth of the anterior chamber during surgery. “Use of a capsular tension ring, a lower irrigation rate, and a viscoelastic barrier in the area of zonular dialysis can serve to avoid this intraoperative complication,” he said. Capsular tension rings Capsular tension rings (CTRs) are often used to manage zonular instability in pseudoexfoliation patients, but surgeons differ in their opinions on whether or not to insert them universally in all pseudoexfoliation patients. Drs. Hart, Gedde, and Giaconi agreed that CTRs do not eliminate the risk of late dislocation, but do provide other intraoperative and postoperative advantages. Dr. Hart chooses to place CTRs in all of his pseudoexfoliation patients. Dislocations are impossible to predict, he said, and with a CTR in place, the surgeon has 360 degrees of access to refixate the lens if that happens. This is especially helpful when considering that many pseudoexfoliation patients are at risk of developing glaucoma— ideally, the lens repair should allow the patient to undergo glaucoma surgery later if it is needed, he said. A CTR also keeps the capsular bag open if the lens dislocates, so it is much less likely that the vitreous will prolapse during the lens repair, he added. Dr. Gedde, on the other hand, is selective in the use of CTRs in pseudoexfoliation patients, as there is potential for iatrogenic capsule and zonule injury with CTR insertion. He will use a CTR if there is less than or equal to 4 clock hours of zonular dialysis and/or mild phacodonesis, and a sutured modified CTR or capsule tension segment for more severe dialysis. CTRs redistribute stress among all the zonules and reduce rates of asymmetric capsular contraction, said Dr. Giaconi, but not all pseudoexfoliation patients have weak zonules and not all will end up with a dislocated lens. She will place a CTR if she sees zonular dialysis in one quadrant or if she suspects mild phacodonesis. Surgeons also face the challenge of determining the optimal time to insert the device during the procedure. “A CTR may impede cortical removal, and I prefer to delay implantation as long as possible during the case for this reason,” said Dr. Gedde. continued on page 12