EyeWorld Asia-Pacific December 2012 Issue

33 EWAP Cataract/IOL December 2012 Figure 3. Return of the capsulorhexis to its previous size after decompression of the capsule. Source: I. Howard Fine, MD Figure 1. Anterior capsule is tented up by the cannula, fluid wave is moving posteriorly, and capsulorhexis is enlarged (arrows indicate fluid wave). Figure 2. Capsulorhexis is enlarged by the posterior loculated fluid pushing the lens forward. Ronald YEOH, MD Senior Consultant, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 Consultant Eye Surgeon & Medical Director, Eye & Retina Surgeons #13-03 Camden Medical Centre, 1 Orchard Boulevard, Singapore 248649 Tel. no. +65-67382000 Fax no. +65-67382111 ersryeoh@gmail.com D r Fine’s description of cortical cleaving hydrodissection is a very important intellectual concept not least because it forces us to think logically about the hows and whys of adequate hydrodissection. The technique he describes would ideally result in compete separation of the cortex/epinucleus /nucleus (CEN) mass from the capsular bag each time, obviating the need for much aspiration of remaining soft lens matter. In practice though, it is not usually possible to consistently achieve such a clean and complete separation of the CEN mass from the capsular bag. Nevertheless, it is a technique that many surgeons use and although one may not always achieve complete cortical cleaving hydrodissection, some is better than none! However, I have a slight concern about recommending hydrodissection through the side port at any time. This is because when hydrodissection is performed through the side port, the anterior chamber is basically a closed system and much higher hydrostatic pressures are generated and this can lead to hydrorupture of the posterior capsule. Indeed, the index case of the “pupil snap sign of hydrorupture” that I described in 1996 1 was caused by my performing hydrodissection through the side port. Side port hydrodissection is more efficient for sure; it is also potentially more dangerous and we need to be mindful of this. Dr Fine’s observations on the behavior of the nucleus, e.g., upward movement as hydrodissection progresses have been most instructive. Indeed, I currently teach that the three most important signs of adequate hydrodissection are 1) wave , 2) the forward movement of the nucleus, and 3) the prolapse of the nucleus. To this I often add that pushing and popping the nucleus back into the capsular bag after the forward movement actually confirms that the nucleus has been adequately hydrodissected and that rotation of the nucleus is not required if this is observed. We must not lose sight of the fact that the primary aim of hydrodissection is to mobilize the nucleus. If we can achieve complete cortical cleaving hydrodissection at the same time, that is a bonus! Reference 1. Yeoh R. The pupil snap sign of hydrorupture of the posterior capsule during hydrodissection in phacoemulsification. Br J Ophthalmol. 1996 May;80(5):486. Editors’ note: Dr. Yeoh has no financial interests related to his comments. cortical cleaving hydrodissection frequently eliminates the need for cortical clean-up as a separate step in cataract surgery thereby version of capsular block syndrome as seen by enlargement of the diameter of the capsulorhexis (Figure 2). At this point, if fluid injection is continued, a portion of the lens prolapses through the capsulorhexis. However, if prior to prolapse the capsule is decompressed by depressing the central portion of the lens with the long arm of the cannula in a way that forces fluid to come around the lens equator from behind, the cortical–capsular connections in the capsular fornix and under the anterior capsular flap are cleaved. eliminating the risk of capsular rupture during cortical clean-up. In a large percentage of cases with 19 gauge tips, less frequently with 20 gauge tips, cortical clean-up is not necessary as a separate step in that during the mobilization of the epinucleus, the cortex is mobilized at the same time. We generally hyrdodissect in two aliquots: one through each of two side-port incisions with decompression following the injection of each aliquot. We then try to rotate the lens within the capsular bag. A small capsulorhexis, 5-5.5 mm, optimizes the procedure. The large anterior capsular flap makes this type of hydrodissection easier to perform. The anterior capsular flap is elevated away from the cortical material with a 26-gauge blunt cannula (e.g., Katena, K7-5150) prior to hydrodissection. The cannula maintains the anterior capsule in a tented-up position at the injection site near the lens equator. Irrigation prior to elevation of the anterior capsule should be avoided because it will result in transmission of a fluid wave circumferentially within the cortical layer, hydrating the cortex and creating a path of least resistance that may disallow later cortical cleaving hydrodissection. Once the cannula is properly placed and the anterior capsule is elevated, gentle, continuous irrigation results in a fluid wave that passes circumferentially in the zone just under the capsule, cleaving the cortex from the posterior capsule in most locations (Figure 1). When the fluid wave has passed around the posterior aspect of the lens, the entire lens bulges forward because the fluid is trapped by the firm equatorial cortical–capsular connections. The procedure creates, in effect, a temporary intraoperative continued on page 34