Relative afferent pupillary defect in eyes with retinal detachment.

Relative afferent pupillary defects were measured before and after surgery in 38 patients with unilateral rhegmatogenous retinal detachment. All 38 patients were measured preoperatively and the mean (+/- SD) pupillary defect was 1.4 +/- 0.7 log units. The afferent pupillary defect decreased in 36 of the 38 patients after successful scleral buckling operations (postoperative mean = 0.4 +/- 0.3 log units). Twenty patients had defects postoperatively of 0.3 log units or less, and seven of these had no measurable defects at all. A prediction model, using the variables of total number of peripheral quadrants detached and whether the macula was detached, yielded the following prediction equation: Relative afferent pupillary defect (log units) = 0.35 X (total quadrants) + 0.68 X macula detachment. This means that the detachment of each peripheral quadrant of retina caused about 0.35 log units of defect, whereas detachment of the macula caused 0.68 log units. The standard error of this estimate was rather large (+/- .65 log units); therefore, the size of the afferent pupillary defect can only roughly predict the extent of the retinal detachment and vice versa.