Clinical Alert

January 3, 1995

Clinical Alert to Ophthalmologists and Neurologists

Dear Colleague:

This letter is to inform you of findings from the Ischemic Optic Neuropathy Decompression Trial (IONDT) that warrant your attention prior to publication of the results. This randomized, controlled clinical trial is supported by the National Eye Institute (NEI), part of the National Institutes of Health, and is being conducted at 25 clinical centers nationwide. The study is headquartered at the University of Maryland at Baltimore.

The IONDT compared the safety and efficacy of optic nerve decompression surgery plus careful followup versus careful followup alone in patients with non-arteritic ischemic optic neuropathy (NAION).

All patients were diagnosed with NAION by IONDT neuro-ophthalmologists. In the study, decompression surgery was standardized and each physician’s surgical ability was reviewed by the IONDT’s Surgical Quality Assurance Committee. Moreover, all surgeons were required to have previously performed ten or more decompression operations to be certified to participate in the study.

As of September 1994, the study had received and analyzed outcome data for 244 patients. Of these patients, 119 had been randomized to decompression surgery and 125 to careful followup, with 95 and 91, respectively, having completed six months of followup.

Preliminary results indicate that decompression surgery was no better than careful followup, based on detailed statistical analysis. These results include:

• At six month of followup, 43 percent of careful followup patients improved three or more lines of vision (using the New York Lighthouse chart). In the surgery group, 33 percent had a three-line improvement in their vision over the same followup period. Thus, surgery has no positive effect on outcome compared to careful followup.
• Twelve percent of eyes in careful followup lost three or more lines of vision at six months, compared to 24 percent in the surgical group. This suggests that decompression surgery may be harmful.
• The IONDT’s finding that 43 percent of careful follow patients had spontaneous improvement of three of more lines in their vision (See Bullet 1) is much higher than previously reported. Most of the earlier studies had indicated a spontaneous improvement rate of ten percent or less.
• No beneficial surgical effect on visual acuity was seen in patients with progressive visual loss.

In late October 1994, the IONDT’s Data and Safety Monitoring Committee reviewed these preliminary findings and recommended that recruitment to the IONDT cease with enrolled patients continuing to be followed. Thereafter, the NEI halted patient recruitment, and study investigators reviewed the data. A scientific paper was submitted to the Journal of the American Medical Association for expedited review in mid-November, was accepted, and will be published in an upcoming issue of the Journal.

Based on the above results, we conclude that optic nerve decompression surgery is not an appropriate treatment for NAION. We can offer no recommendation regarding the safety and efficacy of this surgery for other conditions.

Sincerely,


Carl Kupfer, M.D.
Director
National Eye Institute

Shalom Kelman, M.D.
IONDT Chairman
University of Maryland at Baltimore
School of Medicine

Kay Dickersin, Ph.D.
Director, IONDT Coordinating Center
University of Maryland at Baltimore
School of Medicine