The only methods of preventing glaucoma involve medications or surgery. For open-angle glaucoma, a study of more than 1,600 people with elevated IOP and no other signs of glaucoma showed that IOP-lowering eyedrops delay the development of glaucoma.
Called the Ocular Hypertension Treatment Study, it found that 4 percent of people who took IOP-lowering medication developed glaucoma over a five-year period, compared with 10 percent of those who did not take these medications. A follow-up study found that IOP-lowering eyedrops cut the development of open-angle glaucoma in half among blacks.
For closed-angle glaucoma, making a hole in the iris with a laser (a procedure called laser iridotomy) can be preventive, although the decision to perform this treatment depends on a variety of factors.