The effects of prostaglandins on the intraocular pressure of the rabbit.

1. The effects of intracameral injections of prostaglandins E(1), E(2), F(1a), F(2a), and A(1) were studied on the intraocular pressure (IOP) of rabbits anaesthetized with urethane.2. With the exception of prostaglandin F(1a), all the prostaglandins studied were found to be capable of producing a large, sustained rise in IOP, accompanied in many cases by miosis.3. A marked decrease in response to repeated injections was found with all the prostaglandins studied; this effect was more pronounced following a large initial response to the prostaglandin.4. The descending order of potency in their ability to raise IOP was as follows: prostaglandin E(1) approximately E(2)>F(2a)>A(1)>F(1a).5. Intracameral injections of prostaglandins E(1) and E(2) resulted in an increase in the protein content of the aqueous humour, which was related to the magnitude of the sustained increase in IOP.6. Stabilization of the blood-aqueous barrier with polyphloretin phosphate markedly reduced both the IOP response and the effect of prostaglandin E(2) on the protein content of the aqueous humour.7. It is concluded that the production of local vasodilatation and increased permeability of the blood-aqueous barrier play an important part in the effect of prostaglandins on the IOP. The involvement of prostaglandins in the response of the rabbit eye to irritation is discussed.