Purpose: Intraocular lens (IOL) opacification is a rare but serious complication that may necessitate its exchange. The use of intraocular gases is a known precipitant. Descemet stripping endothelial keratoplasty (DSAEK) involves injecting air into the anterior chamber. IOL opacification has been described after this procedure; however its incidence is currently unknown. Methods: A retrospective review of case notes from a single center of all patients undergoing DSAEK, who were either already pseudophakic or had simultaneous cataract surgery. Cases with IOL opacification were analyzed, and any risk factors were identified. Results: One hundred sixty-eight DSAEK were performed on 154 eyes of 137 patients. Fifty-four cases had simultaneous cataract surgery with implantation of an IOL. Fifteen (9.7%) eyes developed IOL opacification. This had a distinctive pattern, being limited to the anterior lens surface, in the pupillary zone. Median time interval from keratoplasty to the first observation of IOL opacification was 17 months (range, 4-34 months). The only statistically significant risk factor was rebubbling of detached endothelial grafts. Rebubbling was performed in 62.5% (10/15) of cases with IOL opacification, compared with 23% (32/139) with no opacification (P = 0.0009). Conclusions: This is the first study to report the incidence of IOL opacification after undergoing DSAEK. Although the mechanism is unknown, multiple injections of air into the anterior chamber statistically increase the risk of IOL opacification.