No data could be found in the literature on the influence of carnosine on effects produced by prostaglandins (PG). On instillation into the conjunctival sac or by subconjunctival injection, PG of the El, E2, and F2~ groups cause an acute rise of intraocular pressure (lOP) in laboratory animals; this prostaglandin-induced ocular hypertension arises as a result of increased formation of intraocular fluid. This is the result of disturbance of the permeability of the blood-aqueous humor barrier. The increase in microvascular permeability is greatest in the anterior part of the uveal tract of the eye [i, 4, 6, 14].