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Incision creation and closure a complex part of cataract surgery
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Critical factors in successful cataract surgery incision creation and closure include size, configuration, location and adjuncts such as wound hydration, sutures and sealants. There is no doubt that size matters in incisions. Smaller incisions, regardless of location, configuration and closure, seal better and induce less leakage, bleeding and astigmatism.
My friend Howard Fine used to teach that paracentesis incisions less than 1 mm in length were “free,” suggesting that it is safe to place several of them at surgery, for example when using iris or capsular hooks, without complication, measurable induced astigmatism or higher-order aberrations. However, a poorly constructed or radial paracentesis incision can generate a copious leak and even result in hypotony and a shallow or flat chamber, especially when placed in clear cornea.
Wound configuration is thus also critical in regards to wound sealing and ease of surgery. Even an incision large enough to perform extracapsular cataract surgery can be self-sealing and sutureless when properly configured. A three-plane square Descemet’s membrane valve incision with minimal trauma is ideal. A smaller incision with significant trauma or heat damage during cataract removal or lens implantation will induce more astigmatism and seal less well than a larger one that avoids such intraoperative trauma, so incisions should be properly sized for the task at hand.
Richard L. Lindstrom
Incisions placed under conjunctiva or with a smooth angled entry through the cornea are more comfortable for the patient. For me, this has been a disadvantage of so-called Lieberman incisions with a deep groove and also those made with the current generation of femtosecond lasers. I therefore prefer exquisitely sharp metal or gem blades for my incisions.
Incision location is also important. Incisions closer to the corneal apex induce more astigmatism and higher-order aberrations per millimeter in length. This can be helpful when trying to correct astigmatism with a cataract or corneal relaxing incision or detrimental when trying for minimal surgically induced astigmatism.
Incision location affects wound healing. Incision that are in vascular tissue heal faster and more securely than those in avascular tissue, such as the more central clear cornea. I like my cataract incisions to originate in the sclera or perilimbal capillary plexus and to bleed when they are created. Those of us with a lot of incisional keratotomy experience know that the unsutured clear corneal incision can be opened with ease even several decades later. Even when sutured, as in keratoplasty, these incisions never achieve the tensile strength exhibited by those that originate in vascular tissue.
Finally, work by many, including Paul Ernest, MD, Peter McDonnell, MD, Sam Masket, MD, and others, confirms that many so-called clear corneal cataract incisions leak in the early postoperative period. Wound hydration can help. Sutures also are a time-honored adjunct, but recent studies suggest they are far from ideal, with the potential for persistent wound leak, discomfort, suture-associated inflammation or infection, and induced astigmatism. I am finding the recently approved ReSure wound sealant from Ocular Therapeutix, for whom I consult, helpful in select cases.
A properly sized and well-constructed incision in the appropriate location, closed in a watertight manner at the end of surgery, is critical to a successful operation. A good incision also significantly affects the patient’s postoperative outcome, quality of vision and level of comfort, impacting overall satisfaction. While simple on the surface, the subject of wound creation and closure is a complex one, but one well worth mastering.