Abstract：Objective To investigate the effects of orthokeratology (OK) on peripheral refraction and its working mechanism. Methods This was a self-controlled study. Eleven enrolled children underwent subjective refraction， corneal topography and peripheral refraction measurements before and one month after OK lens wear. Only right eyes were tested. During peripheral refraction measurements， children were required to view seven consecutive targets at a distance of 5 m from 30°nasal to 30°temporal. An infrared open-field autorefractor was used to obtain six peripheral refractions and one central refraction. The difference between peripheral refraction and central refraction was identified as the relative peripheral refraction (RPR). RPR changes at each peripheral angle were recorded. The seven corneal positions corresponding to each peripheral angle were identified by simulating the Gauss Optical System and the changes in their sagittal refractive power were recorded and calculated. RPR values before and after lens wear were compared using a paired t test. RPR changes and corresponding sagittal corneal refractive power changes were analyzed with a Pearson correlation test. Results RPR values were hyperopic at all peripheral angles before OK lens wear (except 10° nasal)， showing asymmetry between nasal and temporal visual fields， with more hyperopia in the periphery and temporal visual field. RPR values shifted to myopia at all peripheral angles (except 10°nasal) after 1 month of OK lens wear， with higher myopia in the periphery and temporal visual field. When compared with pre-OK values， differences were statistically significant at 30° nasal and 10°， 20°， 30° temporal (t=2.32， P=0.043； t=3.01， P=0.013； t=5.92， P<0.01； t=7.08， P<0.01). Peripheral refractive changes were significantly correlated to sagittal corneal refractive power changes (r=0.842， P=0.018). Conclusion The OK lens reshapes the anterior corneal surface， making the cornea flatter in the center and steeper in the mid-periphery， thus bringing a myopic shift to peripheral refraction.
陈志,瞿小妹,周行涛. 角膜塑形镜对周边屈光度的影响及其作用机制[J]. 中华眼视光学与视觉科学杂志, 2012, 14(2): 74-78.
CHEN Zhi,QU Xiao-mei,ZHOU Xing-tao. Effects of orthokeratology on peripheral refraction and its mechanism. Chinese Journal of Optometry Ophthalmology and Visual Science, 2012, 14(2): 74-78. DOI: 10.3760/cma.j.issn.1674-845X.2012.02.003
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