For decades before the initiation of the Ocular Hypertension Treatment Study (OHTS),1no consensus existed among ophthalmologists regarding the treatment of patients with ocular hypertension. Some studies2- 6affirmed the protective benefits of treatment, and other studies7- 12did not support the use of preventive medical therapy. Therefore, it was unclear if early treatment was beneficial. Most of these studies did not enroll a diverse patient population,2- 12others used a single medication as an intervention,2,3,5,6,10and all differed in their definitions of glaucoma. Moreover, questions were raised by health outcomes experts outside the field of ophthalmology regarding whether treatment of glaucoma in general was beneficial.13Thus, a well-designed clinical trial was needed to assist clinicians in determining whether treatment is protective and, if so, which patients would benefit most from treatment.