Decreased aqueous-flare reaction to repeated applications of prostaglandin E2 to the cornea in pigmented rabbits.

To evaluate the effect of single or repeated topical applications of prostaglandin E2 (PGE2) to the cornea on the blood-aqueous barrier, we have measured the extent of flare in the anterior chamber of rabbit eyes at various time intervals. PGE2 was applied to the cornea for 4 min with the use of a glass cylinder in pigmented rabbits. Aqueous flare was measured by a laser flare cell meter. The flare intensity following the second application of 25 or 50 micrograms/ml of PGE2 was smaller than that following the first application. When 50 micrograms/ml of PGE2 was applied every day for 6 days, the flare intensity decreased significantly day by day. After consecutive applications of 10 micrograms/ml of PGE2 at hourly intervals, flare intensity increased up to 3 h, remained elevated from 3 to 5 h, and decreased thereafter. Repeated applications of 10 micrograms/ml of PGE2, every hour for 14 h every Monday, significantly decreased flare intensity week by week. Weekly applications of 50 micrograms/ml of PGE2 did not change flare intensity. This study indicates that the extent of the breakdown of the blood-aqueous barrier in the rabbit eye, as measured by the development of flare in the anterior chamber, is reduced with repeated PGE2 application.