Figure 4. Histograms illustrating evolving changes in the electroretinograms. Average values (mean±SEM) of the positive scotopic threshold response (pSTR) and a- and b-waves are presented as percentages of their basal values in three different experimental groups that were analyzed at increasing survival intervals and sacrificed at 17 (A), 35 (B), or 63 (D) days after lasering. At 24 h after laser treatment, a large reduction can be seen in the amplitudes of all the registered waves when compared to their basal levels. These reductions are maintained over time and do not recover significantly even for the animal group examined at 8 weeks after lasering (C), suggesting that laser treatment induces a permanent functional impairment within the innermost, inner and outer retina.