Corneal Shape Changes after 2.0-mm or 3.0-mm Clear Corneal versus Scleral Tunnel Incision Cataract Surgery

Purpose To compare changes in corneal shape and in regular and irregular corneal astigmatism after 3.0- or 2.0-mm clear corneal incision cataract surgery (CICS) with those occurring after 3.0- or 2.0-mm scleral incision cataract surgery (SICS). Design Randomized, comparative clinical trials. Participants Ninety patients scheduled for bilateral cataract surgery were randomized to 1 of 2 groups: 3.0- or 2.0-mm CICS in the left eye and 3.0- or 2.0-mm SICS in the right eye or CICS in the right eye and SICS in the left eye. Intervention All patients underwent CICS and SICS at the 9-o'clock meridian in fellow eyes. Main Outcome Measures Induced corneal astigmatism was determined using vector analysis, and the averaged changes in corneal shape and irregular astigmatism were examined using videokeratography before surgery and at 2 days and 1, 2, 4, and 8 weeks after surgery. Results For the 3.0-mm incision, induced astigmatism was significantly greater in the CICS group than in the SICS group ( P ≤0.0329) at 2 weeks and later. The average of difference map on videokeratography in the CICS group showed a marked wound-related flattening and coupled steepening around the flattened area at 2 days after surgery, and these changes persisted for up to 8 weeks: the changes were markedly less in the SICS group. Among the irregular astigmatic components, higher-order irregularity in the CICS group was greater than that in the SICS group ( P