AIM:To evaluate the changes of the corneal surface morphology undergoing overnight orthokeratology treatment and assess the effect of optical center deviation in controlling the development of myopia.

METHODS: This was a retrospective clinical study. One hundred and thirty-four children(134 eyes)with myopia aged 10.66±1.79 years were treated with overnight orthokeratology lenses. The examinations of visual acuity, axial length and corneal topography were performed before and 3, 6, 12, 18 and 24mo after wearing orthokeratology. The results of right eye were taken as the object of this study, SPSS19.0 for statistical analysis.

RESULTS: The distance of decentration about 134 children at 3, 6, 12, 18 and 24mo after wearing orthokeratology were 0.84±0.45mm, 0.77±0.40mm, 0.79±0.41mm, 0.78±0.41mm, and 0.79±0.42mm respectively. The difference between these groups were not statistically significant(F=1.187,P=0.319). The mean distance of decentration after orthokeratology treatment was 0.79±0.35mm, the growth of axial length after 24mo was 0.32±0.30mm, the mean distance of decentration divided into 3 groups, mild(<0.5mm)27 eyes, medium(0.5-1.0mm)79 eyes, severe(>1.0mm)28 eyes, the growth of axial length frow 3 groups after 24mo were 0.45±0.34mm, 0.32±0.28mm, 0.23±0.29mm, were statistically significant difference between each groups(F=3.825, P=0.024). By linear-regression analysis, the growth of axial length and the mean distance of decentration after 24mo was statistically significant difference(F=7.246, P=0.008), equation of linear regression was Y=0.478-0.194X. At 24mo after wearing orthokeratology, the mean distance of decentration about 18 eyes with monocular diplopia was 1.18±0.36mm, and 116 eyes without monocular was 0.73±0.31mm, the distance of decentration were statistically significant difference(t=5.59, P<0.01).

CONCLUSION: The degree of decentration tended to be stable after 3mo of orthokeratology treatment and influenced the effect of myopia control and visual quality.