Detection and evaluation of lesions in the retina, optic nerve and ciliary muscle of old rats using a electron microscope.

Spontaneous eye alteration found in retina, ciliary muscle and optic nerve of old female Wistar rats were studied using an electron microscope. Normal ultrastructures and severity of age-dependent changes were defined in all three locations using a qualitative scoring system or morphometric measurements. Degenerative changes of various severity such as vacuolization or loss of receptor membranes in the retina, and fragmentation or swelling of myelin sheaths in the optic nerve were detected in eyes of untreated animals. Only very slight changes e.g. detachment of sarcoplasma and fragmentation or reduction of myofibrils were found in the ciliary muscle. These evaluation methods have been applied to quantify a chemically-induced exacerbation of spontaneous lesions in the retina and the optic nerve.