AIM:To investigate the short-term effectiveness of orthokeratology(ortho-k)on controlling low-to-moderate myopic in Chinese children.

METHODS: There were 271 subjects(271 eyes)enrolled in this study. In total, there were 141 cases aged 9.43±1.10 in the ortho-k group and the spherical equivalent refractive errors(SER)were -2.74±1.15D. The patients were examined at 1, 7, 30, and 90d after they started wearing the ortho-k lenses. There were 130 cases aged 9.37±1.00 enrolled in the control group, with the SER -2.88±1.39D, and the examinations occurred at 6, 12mo after they started wearing single-vision spectacles. Myopic progression was estimated from changes of axial length in both groups. The chi-square test, independent samples t-tests, paired t-tests, Spearman analysis were used to compare the data of the two groups.

RESULTS: The axial elongation was 0.27±0.17mm in the ortho-k group after 1a which was significantly longer than that before wearing(P<0.01); the axial elongation was 0.38±0.13mm in the control groups(P<0.01); the difference on axial elongation between the two groups was statistically significant and the increase of axial length of the ortho-k group was significant less by 28.9% than that of the control group(P<0.01, by independent samples t-test). There was significant negative correlation between axial elongation and initial age in both groups during the one-year period(ortho-k group: r_s=-0.309, P<0.01; control group: r_s=-0.472,P<0.01). The percentages of younger subjects(aged 7.0～9.4)with fast myopic progression(>0.36mm in 1a)were 38% in the ortho-k group and 76.5% in the control group, respectively; whereas those of the older group(aged 9.4～12.0)were lower, reaching 24.3% and 12.9% in the ortho-k and control groups. In patients with SER 5.00～6.00D, the axial elongation in ortho-k group was 57.1% lower than that in control group.

CONCLUSION: Ortho-k lens is effective to control myopic progression in children with low-to-moderate myopia. In particular, it reduces the percentage of younger children with fast progression and has a better effect of controlling myopic progression with higher degrees of myopia.