Design, methods, and conduct of the Optic Neuritis Treatment Trial.

The Optic Neuritis Treatment Trial (ONTT) was an investigator-initiated, multi-centered, randomized, controlled clinical trial supported by cooperative agreements and grants. It was designed to evaluate the efficacy and safety of oral prednisone or intravenous methylprednisolone followed by oral prednisone as compared with oral placebo. The primary outcome measures were contrast sensitivity and visual field; secondary measures were visual acuity and color vision. Four hundred fifty-seven patients were followed for a minimum of 6 months and a maximum of 3 years. This article describes the design and the methods used to implement the ONTT.