PUBLICATION EXCLUSIVE: Three rules for corneal phaco incisions

Over the last two decades, cataract surgery has evolved from scleral incisions to corneal incisions, from retrobulbar anesthesia to topical anesthesia, and from rigid IOLs to injectable IOLs. Currently, most surgeons use a corneal incision during cataract surgery because it allows less anesthesia, faster recovery, enhanced access to the anterior chamber and excellent visual outcomes. Residents now start learning cataract surgery with corneal incisions and then learn scleral tunnels later in their training. But be warned that a poorly constructed corneal incision can start a cascade of problems during cataract surgery and could put the patient at a higher risk for complications. I have developed three rules of corneal incisions to help young surgeons learn this critical step of cataract surgery.

Rule 1: Stay peripheral

The best corneal phaco incisions are the ones that barely nick the limbal blood vessels. This is because they are peripheral, far from the visual axis, and produce less astigmatic effect. In addition, the vascular nature allows for more secure and better long-term sealing. A completely avascular corneal incision only heals to a small fraction of its original strength and can be opened even years later with relatively blunt instruments. A corneal incision that nicks the limbal blood vessels will seal securely and return to a high level of strength. This type of incision cannot easily be reopened and will have to be recut in the rare chance that another procedure is warranted in the future.

Placing the incision at the temporal position is more advantageous than placing it superiorly (Figure 1). This is because the temporal limbus is farther from the visual axis than the superior limbus, and thus the temporal incision will induce less astigmatism. In addition, most cataract patients are elderly and have against-the-rule astigmatism, which actually benefits from the placement of incisions at the 180° temporal meridian. When in doubt, a near-clear incision is certainly better than a truly clear corneal incision. If making the incision with a femtosecond laser, care should be taken to align the interface accurately. In most situations, a vascular, near-clear incision is better than an avascular, truly clear corneal incision.

Click here to read the full publication exclusive, Back to Basics, published in Ocular Surgery News U.S. Edition, August 25, 2017.