Objective: This study aims to compare the increase in refractive error and axial length, variation of endothelium cells, and ratio of corneal staining between two regimens of high myopia-partial reduction orthokeratology (ortho-k) in children.
Methods: The present clinical prospective study recruited 102 high-myopia subjects (204 eyes). These subjects were randomly divided into three groups: (1) ortho-k group 1, subjects with a target myopia reduction of 6.00 D; (2) ortho-k group 2, subjects with a target myopia reduction of 4.00 D; and (3) control group, the refractive error of subjects was corrected using a pair of single-vision spectacles. Vision acuity, refractive error, and the cornea were examined at baseline, and at 2 days, 1 week, 1, 3, 6, and 12 months after commencing lens wear. The measurement of the axial length of the eyeball and a corneal endothelium examination were performed at baseline and at 12 months.
Results: The uncorrected vision acuities improved in subjects in these groups after treatment with ortho-k. Furthermore, the diopters of myopia and corneal curvature significantly decreased at 1 month, and the values continuously improved at 12 months, when compared with subjects at 1 month (P<0.05). Subjects in the control group had a significant increase in refractive error (0.565±0.313 D) and axial length (0.294±0.136 mm), when compared with subjects in the ortho-k-treated groups (P<0.05). However, there were no significant differences in changes in refractive error and axial length between ortho-k groups 1 (0.101±0.176 mm) and 2 (0.123±0.193 mm) at 12 months (P>0.05). Furthermore, subjects in group 1 (28.97%) had a higher rate of corneal staining, when compared with subjects in group 2 (13.06%) (P<0.05).
Conclusion: The two ortho-k regimens, target reduction of 6.00 D and target of 4.00 D, had similar effects in controlling the increase in axial length and refractive error in high-myopia children. However, subjects with a target myopia reduction of 6.00 D had a higher rate of corneal staining than in subjects with a target myopia reduction of 4.00 D.