Multiple linear regression-analysis of variance was used to define relationships between final visual acuity and several parameters in 31 patients with reattached primary rhegmatogenous retinal detachments. Older patient age, preoperative macular detachment, clinically visible macular lesions, greater detachment duration and extent, and higher subretinal fluid butyrylcholinesterase activity were all inversely related to final acuity. The relationship of each parameter to final acuity, in conjunction with and apart from all the other parameters, was defined. Collectively the parameters accounted for 85% of the variation about the mean of the clinically observed finally acuities. The parameters could be weighted to give a generally, reasonably accurate prediction of final acuity at the time of surgery. The findings are consistent with a pathophysiological sequence involving alterations in the choroidal circulation and the blood-ocular barrier of the posterior segment.