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.

Orbscan Topography System 및 A - scan Ultrasonography로 전 방깊 이 훌 측정 하 여 두 기 기 의 신 뢰 도를 평 가하고， A - scan Ultrasonography률 gold standard로 간주 하여 Orbscan Topography System으로 측정한 전방깊이 값의 정확도를 분석하였다. 20안올 대 상으로 Orbscan Topography System 및 A - scan Ultrasonography롤 이 용 하여 측정한 test 와 retest 차이에 대한 평균값은 각각 0.030 :t 0.150 mm와 0.016:t 0.065mm 였다. 또한 54안을 대상으로 Orbscan Topography System과 A - scan Ultrasonography로 측정한 전방깊이 값의 평균은 각각 3.200:t 0.302 mm와 2.999:t 0.239mm로， Orbscan Topography System 측정 값이 더 높았으며 (t = 10.α)3， p<O.αX)1)， 두 기기의 측정값 사이에 높은 상관관계가 있었다 (r = 0.824, p<O.OOül). Orbscan Topography System 측정값을 A - scan Ultrasonography 측정값과 직접 비교하기 위해서는 환산공식이 필요하다.