AIM: To investigate differences between 6.0mm and 6.5mm optical zones in visual quality after FS-LASIK.

METHODS: This was a prospective study. Totally 25 patients(50 eyes)treated with FS-LASIK were included and they were classified into 6.0mm group and 6.5mm group according to optical zone. Objective visual quality was evaluated by OQASⅡoptical quality analysis system(including OSI, Strel Ratio, MTF cut off, OV100%, OV20%, OV9%)and by Sirius to obtain the higher order aberrations parameters(including total HOAs, spherical aberrations, trefoil and coma)at 3mm, 5mm and 7mm pupil sizes. OSDI questionnaire was applied to evaluate patients' subjective visual quality.

RESULTS: At 3mo postoperatively, there were no significant differences in total HOAs, spherical aberrations, trefoil and coma under 3mm pupil size(all P>0.05). Significant differences were only observed in spherical aberrations at 5mm pupil size(P<0.05), and in total HOAs and spherical aberrations at 7mm pupil size(P<0.05).However, there were no significant differences in OSDI scores and OQAS visual quality parameters(P>0.05).

CONCLUSION: HOAs under scotopic conditions could be less with 6.5mm optic zone after FS-LASIK, however, both 6.0mm and 6.5mm optical zones could achieve good subjective and objective visual quality after FS-LASIK.