The idling retina: reversible visual loss in central retinal artery obstruction.

Based on experimental studies, sustained total central retinal artery obstruction (CRAO) lasting more than one and one-half hours has been considered to cause irreversible retinal damage. We have seen five cases of patients with pure CRAO that lasted longer than one and one-half hours who regained significant visual acuity. Three of the patients had a completely spontaneous improvement in visual acuity to 20/50 or better. In addition, the other two patients regained significant vision to 20/80 or better with a modified treatment regimen of acetazolamide, inhalation of 5% CO2 and 95% O2, and aspirin. No foveola-sparing cilioretinal arteries were present in any of the cases. We introduce the concept of reversible retinal ischemia following unsustained CRAO to account for these unexpected improvements in visual acuity.