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Protecting the posterior capsule
With specialized premium IOLs requiring in-the-bag placement, it is becoming increasingly important to protect the posterior capsule during cataract surgery. Single-piece premium IOLs, such as multifocal and toric designs, as well as multi-piece accommodating IOLs, are relatively contraindicated in eyes in which a posterior capsule rupture occurs.
 The smooth end of the chopper is used to protect the posterior capsule as the last piece of cataract is phacoemulsified from the anterior segment. |
Posterior capsule ruptures are most often encountered when a brief period of fluidic surge happens within the anterior segment. Because the volume of the anterior segment is very small, less than 1 cc and sometimes measuring just a dozen drops or less, there is little room for error. Surge happens when the inflow of fluid into the anterior segment is less than the outflow of fluid, even for a fraction of a second. This leads to anterior chamber instability, and the posterior capsule can be inadvertently damaged by the phaco or irrigation and aspiration handpiece. The solution is to always keep the inflow of fluid greater than the outflow of fluid, but there's a challenge: There is just one source of inflow, the bottle of balanced salt solution hanging from the pole, but there are a few sources of fluid outflow, such as the fluid being aspirated by the phaco probe but also the fluid leakage from the main incision and from the paracentesis.
In order to provide an even greater margin of safety, think about the effect of the nuclear pieces weighing down the capsular bag and keeping it safely positioned posteriorly. When the final piece of nucleus is being removed, there is nothing in the capsular bag to weigh it down, and it can start to flutter like a flag if the fluidics aren't optimized. An additional simple step of using the smooth end of the chopper to protect the posterior capsule has helped me preserve the integrity of the posterior capsule even in cases in which there was fluidic surge.