Disruption of the blood-aqueous barrier in rabbits was elicited by infrared irradiation of the iris or by alpha-melanocyte stimulating hormone (alpha-MSH) given subcutaneously. One group of animals was pretreated with topical imidazole before the injection of alpha-MSH. The aqueous flare response was followed and the rabbits were killed at the expected height of the uveitis. The uptake of 3H-prostaglandin E1 in the iris with the ciliary body was then determined and found to be significantly decreased in the rabbits in which alpha-MSH had caused a severe damage of the blood-aqueous barrier. When alpha-MSH caused a more moderate aqueous flare response the prostaglandin uptake was on the contrary significantly increased. Pretreatment of the animals with topical imidazole enhanced parallelly the prostaglandin uptake and the aqueous flare response to alpha-MSH. Topical imidazole per se was found to increase the accumulation of prostaglandin. The prostaglandin uptake values were, however, unchanged in eyes in which infrared irradiation of the iris induced a moderate flare response.
A series of 131 successive hospitalized cases of traumatic hyphaema after blunt injury of the eye were treated with complete bed-rest for 6 days and double eye-patching but without any topical medication. Seven patients (5.3%) had a secondary bleeding. The visual acuities of 115 patients were tested, and 105 regained their normal vision, i.e. 1.0 or over. These results are no better than those reported in series treated with moderate bed-rest for 3-4 days combined with topical administration of corticosteroids and mydriatics. The results indicate that our present treatment may be unnecessarily severe.
MSH, like traumata to the eye, cause a permeability disturbance in rabbits, with protein leakage into the aqueous. The MSH effect was enormously increased by instillation of imidazole or pilocarpine. The MSH effect seems to engage a different mechanism than the prostaglandin-dependent action of other agents.
When applied topically t o a rabbit eye prostaglandin (PG) gives ail inflammatory reaction with a breakdown of the blood-aqueous b a r r i e r and an increased in-
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