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 NeuropathyDecompression Trial (IONDT) that warrant your attention prior to publicationof the results. This randomized, controlled clinical trial is supported bythe National Eye Institute (NEI), part of the National Institutes of Health,and is being conducted at 25 clinical centers nationwide. The study is headquarteredat the University of Maryland at Baltimore.

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

All patients were diagnosed with NAION by IONDT neuro-ophthalmologists. Inthe study, decompression surgery was standardized and each physician’ssurgical ability was reviewed by the IONDT’s Surgical Quality AssuranceCommittee. Moreover, all surgeons were required to have previously performedten or more decompression operations to be certified to participate in thestudy.

As of September 1994, the study had received and analyzed outcome data for244 patients. Of these patients, 119 had been randomized to decompressionsurgery and 125 to careful followup, with 95 and 91, respectively, havingcompleted six months of followup.

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

  • At six month of followup, 43 percent of careful followup patients improvedthree or more lines of vision (using the New York Lighthouse chart). Inthe surgery group, 33 percent had a three-line improvement in their visionover the same followup period. Thus, surgery has no positive effect on outcomecompared to careful followup.
  • Twelve percent of eyes in careful followup lost three or more lines ofvision at six months, compared to 24 percent in the surgical group. Thissuggests that decompression surgery may be harmful.
  • The IONDT’s finding that 43 percent of careful follow patients hadspontaneous improvement of three of more lines in their vision (See Bullet1) is much higher than previously reported. Most of the earlier studieshad indicated a spontaneous improvement rate of ten percent or less.
  • No beneficial surgical effect on visual acuity was seen in patients withprogressive visual loss.

In late October 1994, the IONDT’s Data and Safety Monitoring Committeereviewed these preliminary findings and recommended that recruitment to theIONDT 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 MedicalAssociation for expedited review in mid-November, was accepted, and willbe published in an upcoming issue of the Journal.

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


Carl Kupfer, M.D.
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