Methanol poisoning. A rodent model with structural and functional evidence for retinal involvement
T. G. Murray, T. C. Burton, C. Rajani, M. F. Lewandowski, J. M. Burke and J. T. Eells
Department of Ophthalmology, Medical College of Wisconsin, Milwaukee 53226.
Methanol ingestion can lead to visual impairment, central nervous system
dysfunction, or death. The extent of ocular involvement has been difficult
to determine because the toxicity is restricted to humans and nonhuman
primates due to species differences in methanol metabolism. A rodent model
of methanol toxicity recently developed by us was used to evaluate retinal
dysfunction in methanol poisoning. Formic acidemia and visual toxic
reactions developed in methanol-intoxicated rats. Electroretinographic
analysis indicated a significant early deficit in b-wave amplitude followed
by a temporally delayed, lesser reduction in a-wave amplitude. Histologic
evaluation of the eyes 60 hours after methanol administration revealed
generalized retinal edema and vacuolation in the photoreceptors and retinal
pigment epithelium. Ultrastructural examination showed swelling and
disruption of the mitochondria in photoreceptor inner segments, optic
nerve, and the retinal pigment epithelium. These studies document direct
retinal involvement in this nonprimate model of methanol toxicity.
