Functional deficits resulting from laser-induced damage in the rat retina

Background and Objectives: To determine the threshold for electrophysiological detection of functional changes after laser photocoagulation in rats, and to correlate the functional damage with retinal morphology. Study Design/Materials and Methods: Argon-laser lesions, covering a quarter or half of the retina, were produced in the right eyes of 25 rats. Eyes were evaluated by flash electroretinography (ERG) and histologically at 3, 21, and 60 days after lasering. Results: Lasering of half the retina, but not of a quarter, produced a significant decrease in signals at all time points. Some functional recovery was evident 60 days after injury, and was consistent with concurrent morphological healing. Conclusions: In rats, lasering of half the retina, but not a quarter, leads to significant deficits in outer retinal functions over a 2-month period. Thereafter some recovery occurs, presumably as a result of migration of photoreceptors from undamaged areas and their retinal remodeling.