We retrospectively compared the visual acuity and degree of background diabetic retinopathy in 32 consecutive patients with diabetes who had cataract surgery in one eye (study group) and compared them with the visual acuity and degree of diabetic retinopathy in 32 patients with diabetes who had not had cataract surgery (control group) to determine if the retinopathy was asymmetric and worse in the operated-on eye. Twenty-three (72%) of the 32 study patients had asymmetric retinopathy (with the more severe retinopathy in the eye that underwent cataract surgery in each case) compared with three (9%) of the control group (P < .0005). The eyes that had cataract surgery did poorly in terms of visual acuity with no eyes achieving 20/20 or 20/25, only three eyes achieving 20/30 or 20/40, and 16 achieving 20/100 or worse.