AIM: To evaluate the long-term efficiency and safety of overnight orthokeratology in myopia correction and control in adolescents.

METHODS: Sixty-five myopia adolescents treated in our hospital from August 2011 to February 2012 were retrospectively analyzed and followed up to 2a. Among them, 35 cases(67 eyes)wearing overnight orthokeatology were included as trial group, and 30 cases(60 eyes)wearing spectacles were included as control group. The trial group were divided into 2 subgroup according the myopic grading in the initial visit: subgroup A(35 eyes, ≤-3.00D), B subgroup(32 eyes,>-3.00D and ≤-6.00D). In the trial group, slit lamp, visual acuity, refraction, intraocular pressure, corneal tomography were collected before wearing overnight orthokeratology, 1d, 1wk, 1month, 3mo, and every 6mo after wearing overnight orthokeratology,with axial length, corneal thickness, anterior chamber depth, corneal endothelial cell count, abjective refraction and tear film were also collected before and 2a after wearing overnight orthokeratology. In the control group, slit lamp, visual acuity, refraction and intraocular pressure were collected before wearing and 2a after wearing spectacles. Paired t test were used to compare the intragroup difference. One-way analysis of variance(ANOVA)was used to compare the differences among the groups. P<0.05 was considered statistically significant.

RESULTS: The uncorrected visual acuity of the trial group was improved obviously after wearing Orthokeratology Lens 1d, the visual acuity of a group patients improved more significantly. The corneal curvature(including vertical curvature and horizontal curvature)of the trial group became more flat after wearing Orthokeratology Lens 2a and stopped 2 wk; The length of ocular axis was also increased, the growth rate of B group(0.33±0.31)mm was lower than that of group A(0.43±0.25)mm; Subjective refraction of myopia was increased 0.68±0.49D than wearing Orthokeratology Lens before, but compared with the growth(2.08±0.57)D of the control, the effect of myopia control was more obviously. Grade of dry eye was more severely than that of wearing Orthokeratology Lens before, but there was no significant difference between groups A and B. Compared with wearing Orthokeratology Lens before, corneal thickness, anterior chamber depth, corneal endothelial cell number and the intraocular pressure were all no significant differences between the trial and control group.

CONCLUSION: Orthokeratology is a safe and effective method for the correction of myopia, and long-term use of Orthokeratology Lens can effectively control the development of myopia. Controlling of moderate myopia is more effective than that of low myopia.