Eyeworld

66 | EYEWORLD | SUMMER 2024 G UCOMA by Liz Hillman Editorial Co-Director About the physicians Inas F. Aboobakar, MD Instructor in Ophthalmology Mass Eye and Ear Harvard Medical School Boston, Massachusetts Michael Greenwood, MD Vance Thompson Vision Fargo, North Dakota I WISH I HAD … Dr. Greenwood, in an interview with EyeWorld, said that he thinks genetic testing is warranted when it will impact surveillance or treatment for the patient. Where it is used now is with people who have a family history of glaucoma and when patients want to know their personal risk factors. Without genetic testing, Dr. Greenwood said those with a family history would need to be seen on a routine basis so any glaucomatous disease is detected early and treatment started. With genetic testing, if a person has a mutation or a higher risk score, it could inform closer monitoring and treatment approaches. If the patient does genetic testing and doesn't have the gene, it saves them a lot of trips to the doctor, he said. Unlike early onset forms of glaucoma, which are caused by a single gene mutation, in adult onset glaucomas, a single gene mutation is not sufficient for disease development in the vast majority of cases. "Instead, you have multiple genetic and environmental factors that interact to influence disease development," Dr. Aboobakar explained. "For primary open angle glaucoma (POAG), there are a few hundred associated genes and around 10 or so for both angle closure and exfoliation glaucoma." With that, to test for the cumulative impact of the mutations for these diseases, a polygenic risk score (PRS) is calculated, Dr. Aboobakar said. "In very simplified terms, in order to calcu- late a glaucoma PRS for a given individual, you sum up all the risk alleles that they carry in all glaucoma-associated genes across the genome. Then, looking at the population distribution of these scores, you can classify an individual into high or low genetic risk groups." Dr. Aboobakar said studies that use large datasets with genetic and clinical information have assessed the clinical impact of PRSs for glaucoma. In one study, she said, clinical out- comes were compared for each decile of PRS. Those in the higher deciles had higher odds of glaucoma development, as well as early age of disease diagnosis, lower RNFL thickness, and greater need for incisional glaucoma surgery. Dr. Aboobakar said that longitudinal studies that have followed cohorts of suspect and early glaucoma have also showed that PRSs are asso- ciated with faster rates of visual field progres- Genetic testing: What's available and what's on the wish list G enetic testing for glaucoma is not quite ready for "primetime," accord- ing to Michael Greenwood, MD, but it's close. Dr. Greenwood and Inas F. Aboobakar, MD, provided their thoughts on the current state of glaucoma genetic testing, its potential utility for patients, and what's on the wish list. Current status and utility Dr. Aboobakar, at the 2024 ASCRS Glaucoma Day, gave a comprehensive overview on the cur- rent status of genetic testing for glaucoma. "When some people think of the genetics of glaucoma, they may think of an alphabet soup of random gene names," she said on the podium. "Hopefully, I can convince you that it's more than that, and it's likely something that will play an important role in both clinical glaucoma care as well as medicine in general in the years to come. It's therefore important to become familiar with the basics." Gene-based panels are already commercial- ly available, though Dr. Aboobakar said nearly all are for early onset glaucoma. It's important to ensure the lab performing the genetic test is CLIA certified, and referral to a genetic counsel- or should be considered. Dr. Aboobakar said these tests could be used to screen first-degree relatives. If the relative also carries the gene mutation, they would war- rant close surveillance, whereas if they do not have the variant, their risk is relatively similar to the general population. Jeff Pettey, MD, Cataract Editorial Board member, shared what he wishes he had: For global blindness, I wish we had a glaucoma procedure as effective as trabeculectomy that was as simple to perform as cataract surgery. I WISH I HAD ...

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