Eyeworld

112 | EYEWORLD | JULY 2021 C ORNEA by Ellen Stodola Editorial Co-Director About the physicians Thomas Dohlman, MD Massachusetts Eye and Ear Boston, Massachusetts Alanna Nattis, DO SightMD Babylon, New York Puneet Singh, MS Medical Student New York Institute of Technology College of Osteopathic Medicine Old Westbury, New York Allan Slomovic, MD Marta and Owen Boris Endowed Chair in Cornea and Stem Cell Research Department of Ophthalmology and Vision Sciences University of Toronto Toronto, Canada Jia Yin, MD, PhD Massachusetts Eye and Ear Department of Ophthalmology Harvard Medical School Boston, Massachusetts Small sample size seemed to be an issue in the papers reviewed. Ms. Singh noted that sev- eral were just case reports, while other studies on the topic were limited to 10–50 patients. "We're seeing a large disparity in sample size as well," she said. "We were hoping that this would set a baseline to get a bigger project rolling and see if this would translate to a larger population for a study." Dr. Nattis added that additional data could be gathered from corneal specialists in a retrospective study. She noted that she has some personal experience using subconjunctival bevacizumab in fellowship training, as well as topical. She found the subconjunctival approach was more efficacious and was well tolerated by patients. Ms. Singh noted that in her review, she found a study comparing the use of subcon- junctival vs. topical bevacizumab. The patients receiving topical treatment ended up going back to subconjunctival because there was subopti- mal regression seen with corneal neovascular- ization. That study suggested it was probably due to a tissue barrier that couldn't be penetrat- ed with topical use. 1 Subconjunctival and intrastromal approaches Allan Slomovic, MD, has explored both subcon- junctival and intrastromal approaches for using bevacizumab. A paper published in Cornea in 2008 2 looked at 10 patients receiving subconjunctival injections of 2.5 mg/0.1 mL. Dr. Slomovic said this yielded very good results. He noted that imaging with a camera and computer software was used to identify the density and the number of clock hours the neovascularization extended. The study results noted that "corne- al neovascularization covered, on average, 14.8%±2.5% (SD) of the corneal surface before the injections, compared with 10.5%±2.8% (P=0.36, t test) after bevacizumab injection. Therefore, bevacizumab decreased corneal neo- vascularization by 29%." This led to the conclu- sion that bevacizumab was well tolerated with a subconjunctival approach and was effective for partial regression of corneal neovascularization. Applications for bevacizumab in corneal surgery N umerous studies have looked at different approaches to using beva- cizumab and other anti-VEGF agents for anterior segment surgery. Several experts discussed their use and study of bevacizumab, particularly relating to corneal neovascularization and in corneal transplants. Different approaches—subconjunctival, intras- tromal, and topical—were discussed. Subconjunctival bevacizumab use for corneal graft survival Alanna Nattis, DO, and Puneet Singh, MS, recently examined subconjunctival bevacizumab for corneal graft survival. Though a number of patients do well after corneal transplants, there are some who have a lot of inflammation, Dr. Nattis said. This could be due to infection or possibly preexisting corneal neovascularization, she said, adding that neovascularization can portend a poor prognosis. "We know steroids can be helpful, and clinically, I've had positive experience using subconjunctival bevacizumab for patients with and without corneal trans- plants with significant neovascularization." However, there has not been a large review or many controlled trials in this area. "We thought it was important to look at the litera- ture that was out there," she said. A literature review found little research on the subconjunctival use of bevacizumab, Ms. Singh said, adding that most research was done outside the U.S. Despite this, Ms. Singh said the use of bevacizumab to prevent corneal graft rejection has increased, with corneal neovascularization being a major risk factor for rejection. Its use limits graft rejection and the need for further invasive procedures that may result from neo- vascularization. "We're seeing that it's being used, but there are no set guidelines about the dosage, how to administer it, how to get maximum effect, or whether there's direct adverse effects seen with the drug," Ms. Singh said. Dr. Nattis and Ms. Singh are hoping that their literature review and exploration into this topic may serve as a baseline for future research.

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