Investigative Ophthalmology & Visual Science, Vol 28, 101-105, Copyright © 1987 by Association for Research in Vision and Ophthalmology

ARTICLES AND REPORTS

Ocular trace metal kinetics and toxicology. I. The distribution of intravitreally injected 67Cu++ within intraocular compartments and its loss from the globe

LZ Bito and RA Baroody

Radioactive copper (67Cu++) was injected into the center of the vitreous body of rabbits. The relatively rapid initial loss of 67Cu from the vitreous was associated with its accumulation in intraocular tissues. At 24 hr, 20% of the injected 67Cu was found in the retina, representing the highest 67Cu concentration among all ocular tissues, and this high 67Cu concentration was maintained in this tissue throughout the 10-day observation period. Significant amounts of 67Cu were not detected in the aqueous humor at any time. About one-half of the injected 67Cu was lost from the whole globe in 5 days, but the remaining Cu was retained in the globe during the next 5 days. Eyes that received a large dose of CuSO4 in addition to the tracer showed decreased 67Cu activity in the retina and a slight increase in the aqueous humor. Endotoxin-induced ocular inflammation decreased the rate of 67Cu loss from the vitreous, reduced its accumulation by the retina, and increased 67Cu entry into the aqueous humor. It is concluded that 67Cu is retained in the vitreous and the globe due to its binding by, and/or uptake into, intraocular tissues, especially the retina. Cu does not effectively enter the anterior chamber from the vitreous, apparently due to its effective removal by the ciliary processes, thus ruling out the possibility of identifying the existence of Cu- containing intraocular foreign bodies in the posterior segment of the eye by analysis of Cu in the aqueous humor.