Achieved and Functional Optical Zone in Myopic Eyes With High Astigmatism After Small Incision Lenticule Extraction

PURPOSE: To investigate the achieved optical zone and func- tional optical zone in myopic eyes with high astigmatism after small incision lenticule extraction (SMILE). METHODS: Seventy-five eyes of 75 consecutive patients with myopia before SMILE were included and divided into two groups (no astigmatism group: without astigmatism vs high astigmatism group: with astigmatism > 2.00 diopters). The achieved optical zone, functional optical zone, and corneal aberrations were compared using Scheimpflug imaging at 6 months postoperatively. Correlations between corneal aber- rations and functional optical zone were analyzed. RESULTS: The mean achieved optical zone diameter was smaller in the no astigmatism group than in the high astigma- tism group. There were no significant differences in achieved optical zone among the different meridians in each group. The mean functional optical zone diameter was significantly smaller in the no astigmatism group than in the high astig- matism group. Compared with the programmed optical zone, significant reduction of the functional optical zone was found in the two groups. The reduction of the functional optical zone was significantly smaller in the high astigmatism group than in the no astigmatism group, except for the 60 degrees, 90 degrees, and 120 degrees meridians. There were significant correlations between the functional optical zone area and the induced corneal aber- rations in the high astigmatism group, except for horizontal coma, whereas significant correlations of functional optical zone with total higher order aberrations and spherical aber- ration were detected in the no astigmatism group.