MAR 17, 2008
These two papers highlight details of the Ischemic Optic Neuropathy Decompression Trial (IONDT), a study conducted in the 1990s on the use of optic nerve decompression surgery (ONDS) to treat nonarteritic anterior ischemic optic neuropathy (NAION). They reinforce the fact that before a treatment for a disease process can be accepted as efficacious, the natural history of the disease needs to be defined. This is an important lesson since there is no known treatment for this relatively common disorder, and new treatments with intravitreal medications have recently been reported to be effective.
The first article, written by a member of the steering committee and several of the writing committees for IONDT, provides a history of the rationale for performing the study, the study's findings, and its subsequent effects on NAION treatment. A randomized, single-masked, controlled trial conducted at 25 clinical centers, IONDT was initiated after smaller studies reported conflicting results regarding ONDS' effects on NAION. Preliminary IONDT results indicated that the treatment was not effective, might be harmful, and should no longer be used. Subsequent articles on IONDT, however, provided important information about previously unknown clinical characteristics of NAION patients and the disease's natural history.
The second article, whose author was not involved with IONDT, raised some questions about the definitiveness of IONDT's conclusions about ONDS. The procedure, which was initially reported to improve vision in patients with the progressive form of NAION, went on to also be used in nonprogressive cases before IONDT was conducted and its results known. This author noted that IONDT was underpowered to assess the effectiveness of ONDS in progressive NAION and failed to definitively address the surgery's usefulness in these patients. Furthermore, the author wrote, despite strong efforts by IONDT researchers to ensure surgical uniformity during the study, there were relatively large differences in the technique used among participating surgeons. The study allowed the determination that ONDS for nonprogressive NAION performed by most surgeons was not effective, the author concluded.
Archives of Ophthalmology, November 2007, article 1
Archives of Ophthalmology, November 2007, article 2