Effects of Chronic Retinal Hypoperfusion on the Physiology and Morphology of the Rat Retina

Abstract

Abstract: : Purpose:To determine the effects of chronic retinal hypoperfusion on the physiological and morphological properties of the rat retina. Methods: Chronic retinal hypoperfusion was induced by unilateral and bilateral ligation of the common carotid arteries in anesthetized Long-Evans and Sprague-Dawley rats. Electroretinograms (ERGs) elicited by different stimulus intensities were recorded and histopathological studies performed up to 4 weeks postligation. Results: Injection of India ink in the heart demonstrated perfusion of both retinas following bilateral ligation. The a- and b-waves of the ERGs were significantly depressed by about 50% in the bilateral and unilateral (ipsilateral) ligated animals, although the thresholds were not as altered. The b-waves were more affected than the a-wave so that the b/a wave ratio was less than 1.0, a negative type ERG. There was a progressive decrease in the a- and b-waves with increasing postligation times. The thickness of the outer nuclear layer was markedly reduced but the thickness of the outer nuclear layer was not altered at 4 weeks postligation. Conclusion: Chronic retinal hypoperfusion leads to significant and progressive changes in the physiology and morphology of the rat retina.

Keywords: 396 electroretinography: non-clinical • 448 ischemia • 554 retina