Eyeworld

64 | EYEWORLD | FALL 2024 C ORNEA STRIKE! by Ellen Stodola Editorial Co-Director About the physicians Francis Price Jr., MD Price Vision Group Indianapolis, Indiana Zeba A. Syed, MD Director Cornea Fellowship Program Wills Eye Hospital Philadelphia, Pennsylvania W hen planning cataract surgery, it's important to pay particular attention to patients who may have a compromised cornea or endothelial damage. Francis Price Jr., MD, and Zeba A. Syed, MD, spoke with EyeWorld about considerations for cataract surgery in these eyes. "We have a lot of patients who have already compromised corneas, and the two biggest groups are those with Fuchs dystrophy and those with previous transplants, penetrating grafts, or endothelial keratoplasties," Dr. Price said. "We know the cells naturally die off quick- er in an eye that's had a transplant than in a normal eye, so eyes with a previous transplant typically have lower cell counts. We also know that after cataract surgery in general, people lose cells more quickly than they did before they were operated on." While phacoemulsification techniques have improved significantly, trauma to the corneal endothelium still may occur, Dr. Syed said. This is especially important in patients with preex- isting corneal compromise who have a reduced endothelial reserve. Although corneal edema is typically transient after uncomplicated cataract surgery, edema may be chronic with worsening vision. A common risk factor for compromised cor- neal endothelium is Fuchs dystrophy, a disorder of guttae formation in Descemet's membrane and endothelial dysfunction, Dr. Syed said. The ensuing corneal edema results in decreased vision with diurnal variation, and pain may also develop in advanced cases with superficial bullae formation. A study found that among patients with Fuchs who had cataract surgery, approximately 10% eventually underwent endo- thelial keratoplasty. 1 Another risk factor for postoperative cor- neal edema after cataract surgery is a history of endothelial trauma. Prior glaucoma surgery, including trabeculectomy or tube placement, may have associated endothelial compromise, she said. Possible mechanisms of endothelial cell loss include altered circulation patterns of aqueous humor, intermittent tube-cornea touch, or elevated oxidative and inflammatory mark- ers. 2 Along similar lines, chronic inflammation in patients with a history of anterior uveitis can impact endothelial cell health. 3 When evaluating patients preoperatively, Dr. Syed said certain features forecast further endothelial decompensation after cataract sur- gery. Preoperative microcystic edema, stromal thickening on the slit lamp, low central endo- thelial cell density (<1,000 cells/mm 2 ), and/ or increased central corneal thickness (>640 microns) predict deteriorating postoperative endothelial function. 4 Dr. Syed said that some intraoperative variables that may aggravate endothelial cell loss include the length of surgery, inappropriate use of instruments, excessive phacoemulsifica- tion energy, toxicity from intracameral medica- tions, vitreous loss, and IOL endothelial touch. Phacoemulsification may damage endothelial cells by the production of free radicals, 5 and patients with compromised endothelium are vulnerable to potentially detrimental effects. "Strategies to reduce the risk of endothelial damage during cataract surgery include use Cataract surgery in eyes with endothelial damage This is an intraoperative photo of an eye with Fuchs dystrophy having simultaneous phaco and DMEK. Note how much clearer the view is on the left side where Descemet's membrane has been removed compared with the right side where the view is still obscured by the thickened Descemet's membrane and guttae. Source: Francis Price Jr., MD

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