Clinical Trial: Ischemic Optic Neuropathy Decompression Trial (IONDT)

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title:

Brief Summary: To assess the safety and efficacy of optic nerve sheath decompression surgery for non-arteritic ischemic optic neuropathy (NAION).

Detailed Summary:

Non-arteritic ischemic optic neuropathy (NAION), the most common cause of acute optic nerve disease in older persons, causes permanent and severe visual loss. Visual function can be impaired through decreased central visual acuity or peripheral field loss, or both. NAION strikes both eyes in up to 40 percent of affected patients. The incidence of NAION has been estimated at 2.3 per 100,000 persons over the age of 50 years and 0.54 per 100,000 for all ages. Estimates of the number of new cases seen each year in the United States range from a low of approximately 1,500 to a high of 6,000.

NAION has been hypothesized to be caused by vascular insufficiency leading to optic nerve head ischemia. There is general agreement that NAION results from transient non-perfusion of nutrient vessels. The wide range of visual field defects and visual loss with NAION can be explained by the extent and number of the blood vessels involved.

Anatomical factors appear to contribute to the vascular event initiating NAION. Clinically, the number of discs congenitally lacking a physiological cup in eyes with NAION is higher than expected. Presumably, in eyes with NAION, these discs have small scleral openings that crowd the nerve fibers as they pass through the restricted space in the optic disc and lamina cribrosa, thereby predisposing to an ischemic spiral.

One current theory holds that NAION begins as a minor ischemic event that later progresses to a major infarction due to congenitally anomalous optic nerves. The inciting ischemic event leads to local anterior nerve edema, and this causes further ischemia.

Optic nerve sheath decompression surgery was reported in 1989 to be of benefit to patients with NAION. The presumed mechanism of action in opt
Sponsor: National Eye Institute (NEI)

Current Primary Outcome:

Original Primary Outcome:

Current Secondary Outcome:

Original Secondary Outcome:

Information By: National Eye Institute (NEI)

Dates:
Date Received: September 23, 1999
Date Started: October 1992
Date Completion:
Last Updated: March 23, 2010
Last Verified: September 2009