Causes of decreased visual acuity after cataract extraction.

We analyzed a consecutive series of cataract extractions to determine the causes of unsuccessful results. Our criterion was a decrease in visual acuity from the preoperative measurement. Fourteen of 1237 eyes met this criterion. In three of the 14, visual acuity was decreased by more than two Snellen lines. Vitreous loss occurred in seven of the eyes. In six of these, cystoid macular edema developed. The reasons for reduced visual acuity were cystoid macular edema (eight eyes), an aggravation of age-related maculopathy (three eyes), and vitreous hemorrhage and herpetic keratitis (one eye each). A branch vein occlusion caused macular edema and vitreous hemorrhage in one eye. From this data, we recognize the importance of avoiding vitreous loss. If it does occur, we recommend that meticulous anterior vitrectomy be performed, with as little manipulation as possible.