During long-term follow-up, about one-quarter of participants in the Ocular Hypertension Treatment study developed visual field loss, according to a study published in JAMA Ophthalmology. Investigators examined the cumulative incidence and severity of primary open-angle glaucoma (POAG) after 20 years of follow-up. A total of 1,636 participants in the Ocular Hypertension Treatment Study were followed from February 1994 to December 2008. In phase 1 (February 28, 1994 to June 2, 2002), participants were randomly assigned to receive either topical ocular hypotensive medication or close observation. In phase 2 (June 3, 2002 to December 30, 2008), both groups received medication. The researchers found that 29.5% of participants developed POAG in one or both eyes. The 20-year cumulative incidence of POAG in one or both eyes was 45.6% among all participants after adjustment for exposure time: 49.3% and 41.9% among participants in the observation and medication groups, respectively. The 20-year cumulative incidence rates of POAG were 55.2% and 42.7% among Black/African-American participants and participants of other races, respectively. For visual field loss, the 20-year cumulative incidence was 25.2%. Using a five-factor baseline model, the cumulative incidence rates of POAG were 31.7%, 47.6%, and 59.8% among participants in the low-, medium-, and high-risk tertiles, respectively.
