Experimental retinal detachment. XI. Furosemide-inhibitable fluid absorption across retinal pigment epithelium in vivo.

Rhegmatogenous retinal detachments were created in one eye of each of six cynomolgus monkeys. Total vitrectomy alone was performed in the fellow eyes. The rate of disappearance of fluorescein sodium injected into the vitreous cavity was measured with kinetic vitreous fluorophotometry. Intravitreal 10(-4)M probenecid was used to inhibit active outward transport of fluorescein. In eyes with retinal detachment, the rate of fluorescein loss from the vitreous cavity was decreased 44% and 22% following intravitreal injection of 10(-4) and 10(-5)M furosemide (Lasix), respectively. Intravitreal 10(-4)M furosemide decreased the rate of fluorescein loss in fellow eyes by 35%. The rate of fluorescein loss via the anterior chamber accounted for only 1% to 8% of the total rate of vitreous fluorescein loss. Thus, it is concluded that intravitreal absorption across the retinal pigment epithelium.