Abstract
Abstract: :
Purpose: To monitor progression of retinal ganglion cell dysfunction in DBA/2J mice, which by 6-9 months develop iris atrophy and secondary angle closure, resulting in elevation of intraocular pressure, cupping of the optic nerve and retinal ganglion cell loss (John et al, IOVS, 1998, 39: 951). Methods: Retinal ganglion cell function was evaluated by means of the pattern electroretinogram (PERG) (Porciatti et al, PNAS 1996, 93: 14955). Transient PERGs in response to abrupt reversal (1 Hz) of gratings of different spatial frequency (0.05-0.4 c/deg) were recorded in young adult (2-3 month old) and older (10-11 month old) anesthetized (Ketamine-Xylazine) mice. The stimulus covered a retinal area of 50 x 56 deg centered on the projection of the undilated pupil. No lenticular opacities were present in both young and old mice. Results: Young DBA/2J mice had normal appearing eyes, whereas older mice had iris atrophy and marked iris transillumination defects. Older DBA/2J mice, as compared to young, had substantially smaller amplitudes (by 30-40% on average). The cone-flash ERG had comparable amplitudes in young and old DBA/2J mice. Conclusions: The decreased PERG amplitude in older, as compared to younger, DBA/2J mice in the presence of comparable cone-flash ERG indicates a selective loss of inner retina function. This suggests that older DBA/2J mice have retinal ganglion cell dysfunction induced by iris changes resulting in secondary angle closure glaucoma. The DBA/2J mouse is a useful model for studying the progression of glaucomatous retinal ganglion cell dysfunction as measured by the PERG. This model has a potential value for monitoring the functional and structural effects of neuroprotective agents.
Keywords: animal model • ganglion cells • electroretinography: non-clinical