Kang Pauline, Gifford Paul, Swarbrick Helen
*PhD, FAAO School of Optometry and Vision Science, The University of New South Wales, Sydney, New South Wales, Australia.
Optom Vis Sci. 2013 Nov;90(11):1237-48. doi: 10.1097/OPX.0000000000000064.
To investigate changes in peripheral refraction, corneal topography, and aberrations induced by changes in orthokeratology (OK) lens parameters in myopes.
Subjects were fitted with standard OK lenses that were worn overnight for 2 weeks. Peripheral refraction, corneal topography, and corneal surface aberrations were measured at baseline and after 14 nights of OK lens wear. Subsequent to a 2-week washout period, subjects were refitted with another set of lenses where one eye was randomly assigned to wear an OK lens with a smaller optic zone diameter (OZD) and the other eye with a steeper peripheral tangent. Measurements were taken again at a second baseline and after 14 days of overnight wear of the second OK lens set.
Standard OK lenses with a 6-mm OZD and 1/4 peripheral tangent caused significant changes in both peripheral refraction and corneal topography. Significant hyperopic shift occurred in the central visual field (VF) while a myopic shift was found at 35 degrees in the nasal VF. OK induced significant reductions in corneal power at all positions along the horizontal corneal chord except at 2.4 mm nasal where there was no significant change and at 2.8 mm nasal where there was an increase in corneal refractive power. A positive shift in spherical aberration was induced for all investigated lens designs except for the 1/2 tangent design when calculated over a 4-mm pupil. Reducing OZD and steepening the peripheral tangent did not cause significant changes in peripheral refraction or corneal topography profiles across the horizontal meridian.
OK lenses caused significant changes in peripheral refraction, corneal topography, and corneal surface aberrations. Modifying OZD and peripheral tangent made no significant difference to the peripheral refraction or corneal topography profile. Attempting to customize refraction and topography changes through manipulation of OK lens parameters appears to be a difficult task.
研究近视患者中角膜塑形术（OK）镜片参数变化所引起的周边屈光、角膜地形图及像差的改变。
为受试者佩戴标准OK镜片，过夜佩戴2周。在基线期以及OK镜片佩戴14个夜晚后测量周边屈光、角膜地形图及角膜表面像差。在为期2周的洗脱期后，为受试者重新佩戴另一组镜片，一只眼睛随机分配佩戴光学区直径（OZD）较小的OK镜片，另一只眼睛佩戴周边切线更陡的镜片。在第二个基线期以及第二组OK镜片过夜佩戴14天后再次进行测量。
具有6毫米OZD和1/4周边切线的标准OK镜片引起了周边屈光和角膜地形图的显著变化。中央视野（VF）出现显著的远视性移位，而在鼻侧VF的35度处发现近视性移位。OK导致沿角膜水平弦的所有位置的角膜屈光力显著降低，但在鼻侧2.4毫米处无显著变化，在鼻侧2.8毫米处角膜屈光力增加。当在4毫米瞳孔上计算时，除1/2切线设计外，所有研究的镜片设计均引起球差的正向移位。减小OZD并使周边切线变陡不会导致水平子午线上周边屈光或角膜地形图轮廓的显著变化。
OK镜片引起周边屈光、角膜地形图和角膜表面像差的显著变化。改变OZD和周边切线对周边屈光或角膜地形图轮廓没有显著差异。试图通过操纵OK镜片参数来定制屈光和地形图变化似乎是一项艰巨的任务。
