Abstract: Objective To investigate the change trend of corneal, internal, ocular imaging quality parameters of subtracted lower order aberration before and after orthokeratology (OK). Design Prospective case series. Participants Thirty-four patients (34 right eyes), mean (11.68±1.70) years old, spherical equivalent diopter (-3.43±1.42) D, who had undergone OK treatment from March to June 2017 in Shenyang Aier Eye Hospital, were chosen for the study and followed up for 6 months. Methods Corneal, internal, ocular imaging quality parameters were measured with the iTrace visual function analyzer under a 5 mm pupil diameter at baseline and after 1 week, 1 month, 3 months, and 6 months of OK lens wearing. Imaging quality parameters include the subtracted lower order aberration modulation transfer function (MTF) at spatial frequencies of 5, 10, 15, 20, 25, 30 cycle/degree (c/d) and strehl ratio (SR). Imaging quality parameters before and after OK were compared with repeated ANOVA. Main Outcome Measures MTF, SR. Results Corneal, internal, ocular low-middle-high spatial frequencies MTF and SR were significantly reduced at different time points after OK in comparison with baseline (all P<0.05). At a spatial frequency of 25 c/d, the corneal MTF decreased after 1 month of OK compared with 1 week after OK (P=0.042). At a spatial frequency of 5 c/d, the internal MTF decreased after 1, 3 months of OK compared with 1 week after OK (P=0.027, 0.004). At spatial frequencies of 10, 20 and 25 c/d, the internal MTF decreased after 3 months of OK compared with 1 week after OK (P=0.029, 0.013, 0.020), and increased after 6 months of OK compared with 3 months after OK(P=0.020, 0.019, 0.042). At a spatial frequency of 15 c/d, the internal MTF increased after 6 months of OK compared with 3 months after OK (P=0.037). The internal SR decreased after 1, 3 months of OK compared with 1 week after OK (P=0.039, 0.015)，and increased after 6 months of OK compared with 3 months after OK(P=0.032). There were no statistical differences among the other time points of post-OK (all P>0.05). Conclusion All the subtracted lower order aberration imaging quality parameters decreased after OK, indicating that the subtracted lower order aberration imaging quality declined. Corneal high spatial frequency MTF, internal low-middle-high spatial frequencies MTF and SR changed between the post-OK groups, but the change of 6 months returned to the level of 1 week after OK. （Ophthalmol CHN, 2020,29: 128-132）

Key words: myopia, orthokeratology, modulation transfer function, strehl ratio