IONDT compared optic nerve decompression surgery (ONDS), which was becoming a widely used treatment for NAION, with careful followup alone, in patients with newly diagnosed NAION. The rationale for the surgery was that NAION was caused by impaired blood flow to the optic nerve and that decompression surgery would restore vision by alleviating pressure surrounding the nerve. Because ONDS was fast becoming the standard of care, evaluation of the safety and efficacy of the procedure was tested in the context of a randomized clinical trial.