Morphological study of the anterior segment of cynomolgus monkey eyes following treatment with prostaglandin F2 alpha.

Topically applied prostaglandin F2 alpha has been shown to lower intraocular pressure in cynomolgus monkeys. In this study the morphological changes, following topical treatment with 4-50 micrograms of prostaglandin F2 alpha for 4-8 days, were investigated. Semiquantitation of (1) accumulation of white blood cells as one sign of inflammation, (2) edema and (3) enlarged spaces between ciliary muscle cells were performed. Eighty sections per eye encompassing the whole circumference were investigated. No accumulation of white blood cells was seen in any of the eyes. Slight edema in the most anterior part of the ciliary processes occurred in most eyes, but only in part of the circumference. These changes could be either directly induced by the prostaglandin treatment or secondary to the decrease in intraocular pressure. The most pronounced change was the dilatation of the intramuscular spaces. These enlarged spaces could explain the physiologically shown increase in uveoscleral outflow.