Higher-Risk Ocular Hypertensives Benefit More From Early Prophylactic Tx Delaying Treatment of Ocular Hypertension: The Ocular Hypertension Treatment Study

Objective: To characterize the efficacy of earlier versus later treatment in preventing primary open angle glaucoma (POAG) in individuals with ocular hypertension. Design: Randomized controlled clinical trial. Participants/Methods: 1636 individuals with elevated intraocular pressure between 24 and 32 mm Hg in one eye and 21 and 32 mm Hg in the fellow eye were randomly assigned to observation or treatment with intraocular pressure-lowering medication. After a median of 7.5 years without treatment, the observation group received medical therapy for a median of 5.5 years. The cumulative proportion of participants developing POAG in the initial treatment and the initial observation groups was compared through 13 years of follow-up. Results: The cumulative proportion of participants in the initial observation group who developed POAG at 13 years was 22% compared to 16% in the initial medication group (P =0.009). Among those participants in the highest third of baseline risk of developing POAG, a significantly higher proportion developed POAG in the original observation group than in the original medication group (40% vs 28%). In the lowest category of baseline risk, little difference was seen in the cumulative proportion developing POAG through final follow-up. Conclusions: It is important to predict higher baseline risk of developing POAG based on intraocular pressure (IOP), corneal thickness, baseline visual field, and optic nerve status. Those individuals at highest risk will benefit from early prophylactic therapy to prevent POAG. Reviewer's Comments: In addition to clinical factors that characterize an individual's risk of developing POAG, it is also important to consider age in making the decision of initiating treatment. Although younger patients may not have a higher rate of developing POAG per year, they have a greater life expectancy and therefore higher cumulative lifetime risk of developing POAG. Given the longer expected duration of exposure to IOP elevation than in older individuals, younger individuals should be considered to be at higher risk and earlier intervention to reduce this risk may be warranted. (Reviewer-Scott D. Smith, MD, MPH).