Abstract: Objective To study the effect on the wavefront aberration using different optical zone in small incision lenticule extraction (SMILE). Design Prospective comparative case series. Participants Thirty-one patients performed SMILE operation。 The right eyes were the study eyes. Methods All the operation were undergone by the same surgeon and with the same laser machine. According to the operative serial number, the patients of the singular number choose 6.0 mm optic zone, and the patients of the even number choose 6.5 mm optic zone during the surgery. The visual acurity, the equivalent spherical diopter, and the wavefront aberration before and after the operation in the two group were recorded and compared. Main Outcome Measures The visual acurity, the spherical diopter, the high order wavefront aberration (RMSh, Coma, Trefoil, Sphere). Results Three months after the surgery, the mean visual acuity of the 6.0 mm group and the 6.5 mm group was 1.20±0.23 and 1.24±0.20, respectively (P=0.534); the mean equivalent spherical diopter was (-0.45±0.32) D and (-0.29±0.42) D, respectively (P=0.235); RMSh was (0.683±0.324) μm and (0.621±0.252) μm (P=0.646), respectively; Coma was (0.124±0.080) μm and (0.100±0.052) μm (P=0.057); Trefoil was (0.060±0.033) μm and (0.061±0.041) μm (P=0.147), respectively; Sphere was (0.007±0.040) μm and (-0.002±0.032) μm (P=0.223), respectively. Compared with the preoperative Coma (0.073±0.050 μm), the post-operation Coma was slightly increased in the 6.5 mm group (P=0.065). The post-operation Coma was significantly increased in the 6.0 mm group compared with the preoperative group (0.075±0.050 μm, P=0.004). Conclusion Operation with 6.0 mm and 6.5 mm optical zone in SMILE both are safe and effective. Although 6.0 mm optical zone may result in the increase of Coma, but it could not result in the increase of other high order aberration.

Key words: small incision lenticule extraction, optic zone, wavefront aberration