EyeWorld India September 2021 Issue

CATARACT EWAP SEPTEMBER 2021 25 by Liz Hillman EyeWorld Editorial Co-Director Contact information Yeoh: ersryeoh@gmail.com This article originally appeared in the July 2021 issue of EyeWorld . It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp. R onald Yeoh, MD, first coined the term pupil snap sign in £99È. 1 Since then, he has been calling attention to the somewhat subtle sign to help surgeons recognize when there has been a posterior capsule rupture that puts the nucleus at risk of dropping into the vitreous. The pupil snap sign is observed during hydrodissection. Dr. Yeoh explained that typically in a normal hydrodissection, the nucleus will lift or come forward, when it is appropriately performed. If there is resistance to the flow of injected fluid, the surgeon might inject harder, Dr. Yeoh continued. “When this happens, the anterior chamber usually deepens and often the pupil dilates more; these are important observations that are a prelude to hydrorupture, and if observed, the injection should immediately be stopped and the anterior chamber vented by pressing on the wound lip,” Review of the pupil snap sign Dr. Yeoh said. If this action isn’t taken and vigorous hydrodissection is continued, the posterior capsule can rupture, hence hydrorupture. At this moment, the surgeon might observe the pupil snap sign, which Dr. Yeoh described as a “sudden, brisk pupillary constriction» of about 3ä¯ of the already dilated pupil. “At the moment of hydrorupture, the abrupt sagging of the nucleus, which was previously lifted up against the back of the pupil by the fluid injected, leads to the brisk pupillary constriction as the nucleus is no longer abutting the pupil,” Dr. Yeoh said. When the pupil snap sign occurs, Dr. Yeoh said the surgeon should observe if there is nucleus tilt. If hydrorupture is suspected, the surgeon should be prepared to elevate/support the nucleus with a 25-gauge needle through the pars plana and deliver it through a larger incision. If the surgeon proceeds with phaco, pressurization of the anterior chamber by a phaco tip could propel the nucleus into the vitreous cavity, Dr. Yeoh cautioned. To avoid this situation on the whole, Dr. Yeoh stressed the importance of careful hydro-dissection. He said to avoid hydrodissection through a sideport, which can lead to higher pressures. Hydrodissection in the setting of a large, dense nuclei or with a small capsulorhexis is another scenario that predisposes to hydrorupture of the posterior capsule. While this complication is not very common, Dr. Yeoh said recognition of the pupil snap sign may prevent the disastrous complication of a dropped nucleus. EWAP Reference 1. Yeoh R. The ‘pupil snap’ sign of posterior capsule rupture with hydrodissection in phacoemulsification. Br J Ophthalmol . £99È;nä\{nÈ. Editors’ note: Dr. Yeoh is Medical Director, Eye & Retina Surgeons, Singapore, and disclosed no relevant financial interests. *ydrodissection with pooling of fluid behind nucleus. *ydrorupture of posterior capsule. The nucleus does not usually drop immediately, only when the phaco tip is inserted, pressuriz - ing the anterior chamber. Source (all): Ronald Yeoh, MD