Purpose: To assess the effect of orthokeratoly lenses on axial elongation in children compared with those wearing spectacles as control. Methods: We enrolled 100 subjects (aged 7-16 years; ortho-k, 50; control, 50) with myopia of -0.50 to -5.00 diopters (D), and with-the-rule astigmatism of -0.25 to -3.00 D. History of eye disease or surgery, strabismus and amblyopia were excluded from the study. The OK lenses used in this study were four-zone, reverse-geometry lenses with a nominal Dk of 140 Fatt unit. The corneal thickness, anterior chamber depth and axial length were measured by noncontact optic biometric device Lenstar LS900 and subjective and objective refraction, visual acuity and corneal curvature were measured before lens wear and the next day, 1 week, 1 month, 2 months, 3 months, 6months, 9months and 12months after lens wear. Results: There were no significant differences in age between groups (p>0.37). In the OK group, the spherical equivalent refractive error and central corneal thickness decreased significantly from -3.78±1.17 D at baseline -0.03±0.1 D, 1.17±0.57 LogMAR at baseline 0.00±0.01 LogMAR, 546.12±22.24 μm at baseline 527.88±23.26 μm 12 months after the treatment (p<0.001), whereas anterior chamber depth remained unchanged (p>0.15). In the spectacle group, anterior chamber depth was significantly increased by 0.04±0.03 mm (p=0.008). In 12 months, axial length increased from 24.99±0.68 to 25.21±0.72mm in the OK group and from 24.99±0.68 to 25.35±0.69 mm in the spectacle group that axial length increase was significantly different between groups (p=0.021). Conclusion: One year of OK in myopic children reduced anterior chamber depth and axial length elongation significantly compared with distance single-vision spectacle wear.

Purpose: To determine the efficacy of toric orthokeratology compared with myopic ortho-k. Methods: We enrolled 60 subjects (aged 7-16 years) with myopia of -0.50 to -5.00 diopters D, and with-the-rule astigmatism of −0.25 to -3.00 D. Subjects who had history of eye disease or surgery, strabismus and amblyopia were excluded. Subjects were divided into two groups, toric ortho-k contact lens wearing group(group-Ⅰ, 30 subjects) and myopic ortho-k contact lens wearing group(group-Ⅱ, 30 subjects). Unaided logMAR visual acuity, refractive error, apical corneal radius, corneal asphericity and central corneal thickness were measured. The corneal thickness, corneal curvature and axial length were measured with Lenstar LS900 (HAAG-STREIT AG, 3098 Koeniz, Switzerland) before wearing ortho-k lenses and after wearing the next day, 1 week, 1 month, 3 months and 6 months of ortho-k. Results: All groups showed statistically significant improvement in unaided visual acuity, increase in apical corneal radius and decrease in central corneal thickness. Compared with toric ortho-k(group-Ⅰ) and control ortho-k(group-Ⅱ) showed significantly less change in visual acuity and corneal topography after the first month of lens wear. The first lens fit success rate was 97% for toric ortho-k lens and 90% for myopic ortho-k lens. Toric ortho-k lenses were effective in correcting low-moderate myopes with moderate-high astigmatism, in particular, cornea astigmatism of -1.5D that reach the goal early stabilization of visual acuity and do not leave a residual astigmatism. Conclusions: Toric lens design lens showed higher first lens fit success and reach the goal early stabilization of visual acuity and do not leave a residual astigmatism for the low-moderate myopic children who had moderate-high astigmatism.