Ischemic Optic Neuropathy Decompression Trial: Evaluation of Change in Pattern Defect and Severity Over Time
Researchers at Johns Hopkins University Bloomberg School of Public Health evaluated the change from baseline to 12 months follow-up in study and nonstudy (fellow) eye visual fields from the Ischemic Optic Neuropathy Decompression Trial (IONDT), a randomized, controlled trial and observational study.
The IONDT enrolled patients 50 years and older with acute nonarteritic ischemic optic neuropathy (NAION). A total of 258 randomized patients had visual acuity less than 20/64; 160 nonrandomized patients had visual acuity better than 20/64 or refused randomization. Interventions were optic nerve decompression surgery (127 patients) or careful follow up (131 patients). Researchers measured visual fields at baseline and at six and 12 months follow up. Using a computerized system, they classified visual field defects by pattern, location and severity and examined changes over time by treatment group, age, baseline comorbidities and change in visual acuity. In fellow (nonstudy) eyes, they assessed change by whether NAION was present at baseline and assessed incidence of NAION by whether a visual field defect was present at baseline.
The study included 245 study eye visual field pairs (179 and 66, randomized and nonrandomized, respectively) for change from baseline to 12 months. Significant changes in defect distribution occurred within the central field for randomized eyes. Superior and inferior altitudinal defects were less severe at follow-up in both randomized and nonrandomized eyes. An association between change in central field severity and change in visual acuity from baseline was evident, but there was no association between visual field change and treatment group, age or baseline comorbidities. Superior and inferior visual field defects present at baseline in nonstudy eyes improved at follow up. Fellow (nonstudy) eyes with normal fields did not have an increased risk of developing NAION compared with eyes with one or greater defects.
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