In a clinical study, 61 patients underwent phacoemulsification with subsequent intraocular lens (IOL) implantation. An intercapsular capsulotomy with phacoemulsification was performed on 23 patients and a can opener capsulotomy with phacoemulsification on 38 patients. Wide-field specular microscopy was performed preoperatively and postoperatively on all of the eyes in the study. The cell counts were not divulged to the surgeon before or at the time of surgery. Average endothelial cell loss for the intercapsular technique was 3.9%; with the can opener technique, the average cell loss was 10.1%. This difference was statistically significant (P less than 0.01). Positive correlations between endothelial cell loss relating to ultrasound time and/or the hardness of the cataract existed for the can opener group only (P less than 0.01). These results demonstrate that a protective effect is provided by the presence of the anterior lens capsule during lens substance removal.