Mechanisms of subretinal fluid resorption in the cat eye.

Small, non-rhegmatogenous retinal detachments (blebs) were made in cat eyes by injecting fluid into the subretinal space, and the time course of fluid resorption was monitored. Blebs made with Hanks' solution over the pigmented RPE resorbed 22% faster than those over the tapetum. Blebs made with a non-ionic solution (isotonic sucrose) took 43% longer to resorb than those made with Hanks' solution, and blebs containing 3 X 10(-3) M sodium cyanide took 32% longer than controls. These results suggest that active ionic transport is involved in the absorption of subretinal fluid in the cat, as it is in the rabbit. Oncotic pressure in the choroid may also contribute to resorption, because blebs made with autologous serum took roughly 3 times longer to resorb than those made with non-proteinaceous Hanks' solution. The retinal vascular system does not appear to contribute, since the resorption time was similar for Hanks' blebs made under normal retina and those made under ischemic retina (produced by occluding retinal branch arteries with argon laser photocoagulation or endodiathermy).