Postoperative corneal shape changes: Microincision versus small-incision coaxial cataract surgery

PURPOSE: To compare changes in corneal topography and in regular and irregular astigmatism after coaxial clear corneal microincision cataract surgery (MICS) and after coaxial small-incision cataract surgery (SICS). SETTING: Hayashi Eye Hospital, Fukuoka, Japan. METHODS: Induced corneal astigmatism was determined using vector analysis. The averaged corneal shape changes and degree of irregular astigmatism were examined using videokeratography preoperatively as well as 2 days and 1, 2, 4, and 8 weeks postoperatively. RESULTS: One hundred twenty eyes of 60 patients scheduled for phacoemulsification were evaluated. Sixty eyes had MICS (2.00 mm), and the 60 contralateral eyes had SICS (2.65 mm). The mean induced corneal astigmatism was significantly less in the MICS group than in the SICS group (P <=.0495) 1 week postoperatively and subsequently. The averaged difference map on videokeratography showed focal corneal flattening corresponding to the incision and coupled steepening around the flattened area 2 days postoperatively in both groups. The flattening and steepening gradually reduced to virtually the preoperative shape by 8 weeks; the changes were significantly less in the MICS group than in the SICS group. Of the irregular astigmatic components, higher-order irregularity was significantly less in the MICS group than in the SICS group up to 2 weeks postoperatively (P <=.0470). CONCLUSION: Induced astigmatism, focal wound-related flattening of the peripheral cornea, and corneal surface irregularity were signficantly less after coaxial MICS than after SICS.