Low b-wave amplitudes in a strain of rabbits with a pigment epithelium defect

When preparing isolated rabbit retinas we found in some animals fundi which were not uniformly dark but had abnormal areas of red coloration. The in s itu electroretinograms (ERG) of 82 rabbits recorded after 1 h of dark adapt ation were checked for abnormalities indicative of a degenerative disorder. The ERGs of eight rabbits with small dark adapted b-waves (less than or eq ual to 250 mu V) were re-recorded and their b-waves found to decline with t ime. The greatest reduction, in three rabbits, was greater than or equal to 150 mu V over 2.5 years. After 1 year, however, the light adapted b-waves were similar to those of rabbits with normal dark adapted b-waves. The majo rity of the progeny of these rabbits also had small b-waves, which became s till smaller in 2 years. Ultrastructural studies of two rabbit retinas of t he first generation showed pathological changes of the pigment epithelium ( Wrigstad, Hanitzsch & Nilsson, Ultrastructural and electrophysiological stu dies of the retina and the retinal pigment epithelium in rabbits with low b -wave amplitudes, in preparation). Evidently there is an inheritable defect in the pigment epithelium which first impairs the rod pathway. (C) 1999 Pu blished by Elsevier Science Ltd. All rights reserved.