Case report: Few previous reports have documented a relative afferent pupillary defect (RAPD) in the eye contralateral to a dense unilateral cataract. We report pupillographic findings of a 55-year-old man with a mature cataract in the left eye and an RAPD in the right eye, whose RAPD disappeared after cataract surgery in his left eye. Using binocular infrared video pupillography, we recorded the pupillary responses of the two eyes simultaneously during an automated swinging flashlight test before and after the cataract surgery. The average contraction amplitude in both eyes was significantly larger when the unaffected left eye was stimulated before the cataract surgery, but this difference in contraction amplitude disappeared after surgery on the left eye.
Comments: An RAPD was shown quantitatively with a pupillographic technique in the eye contralateral to a mature cataract, confirming previous studies that indicate a dense cataract may produce a small but definite RAPD in the contralateral eye. Such an RAPD associated with a dense cataract must be taken into consideration when evaluating patients with unilateral visual loss.