The Ischemic Optic Neuropathy Decompression Trial (IONDT): Design and methods

The objective of the Ischemic Optic Neuropathy Decompression Trial (IONDT) was to investigate the safety and efficacy of optic nerve decompression surgery (ONDS) compared to careful follow-up for nonarteritic ischemic optic neuropathy (NAION) and to observe the natural history of NAION in untreated patients. It was designed as a multicenter, randomized controlled clinical trial. Resource centers included a Chairman's Office, a Coordinating Center, and 25 Clinical Centers at eye centers throughout the United States. The trial's methods were as follows. Eligible patients with visual acuity 20/64 or worse were randomized to ONDS or careful follow-up; eligible patients with visual acuity better than 20/64 made up a natural history cohort and were followed but not randomized to treatment. The primary outcome examined was an increase of three lines or more of visual acuity at 6 months. Additional outcomes were visual acuity at other follow-up times, visual field, quality of life, and morbidity associated with ONDS. Standard quality assurance methodology was used to monitor adherence to protocol. The surgical protocol was monitored by a Surgical Quality Assurance Committee (SQAC). Enrollment began October 8, 1992, and ceased October 20, 1994, because of preliminary findings indicating that surgery was of no benefit and was perhaps harmful. This report describes the design and methods of the trial and the rationale for design elements unique to the IONDT. Specific goals of study design and conduct included achieving an accelerated study start-up and rapidly producing results acceptable to the medical community.