Abstract
Abstract: :
Purpose: To assess changes in outer retinal function following laser –induced retinal damage in the rat, and to determine the threshold for electrohysiological detection of such damage Methods: Standard argon laser lesions were created at the right eye of 16 adult pigmented rats. The laser settings were found in previous studies to result in lesions of the uniform size and configuration, involving mainly the outer retinal layers (514 nm, 200 micron spot at 0.1 W for 0.05 sec). The lesions covered either a quarter or half of the visible retina (experimental group 1 and 2, respectively; 8 animals per group). The left eye served as a normal control. The flash electroretinogram (ERG) was used to assess changes in outer retinal function of the right eye 3, 21 and 60 days post laser. Results:In group 1 (1/4 retinal area lasered), there were no significant changes in function throughout the experimental period. In group 2 (1/2 retinal area lasered) there was a noticeable, but insignificant, decrease in signals (compared to control eyes) 3 days post–lasering. At 21 days, this decrease became significant (P=0.05). Mean (± SD) b–wave amplitudes were 504 ±111 µV and 356 ±130 µV in the control and lasered eyes, respectively.. After 60 days, functional recovery was evident in the lasered eyes. Mean b–wave amplitudes were 570 ± 37 µV and 486 ±105 µV in the control and lasered eyes, respectively (P>0.10) This recovery is consistent with histological evidence of increased photoreceptor density in lesions at this stage. Conclusions:In this work, we demonstrated that lasering of ½, but not ¼, of the retina, leads to significant deficits in outer retinal function measured 3 weeks later. Outer retinal function exhibits some recovery 2 months post–lasering, presumably as a result of migration of photoreceptors from undamaged areas.
Keywords: laser • lesion study • electroretinography: non–clinical