Morphological changes in rabbit ciliary epithelium and blood-aqueous barriers after intravitreal 10(-5) M...

Morphological changes in the ciliary epithelium and blood-aqueous barriers were observed with a tracer, horseradish peroxidase, after 10 microliters of 10(-5) M endothelin-1 was injected intravitreally. A decrease of intraocular pressure and an increase of anterior chamber flare were found, and the structure of the ciliary epithelium changed drastically 6-7 hr after the injection. Swelling of mitochondria appeared in both non-pigmented and pigmented epithelial cells of the ciliary body. Intercellular spaces and ciliary channels were markedly dilated in the iridial processes. Some non-pigmented epithelial cells in both iridial and ciliary processes appeared to be degenerated and necrotic. Horseradish peroxidase leaked into the posterior chamber via extremely dilated ciliary channels and necrotic cells. The dose of 10(-5) M endothelin-1 seems to be so large that a toxic action occurred. The mechanism of the effect of endothelin on intraocular pressure was also discussed.