Plainis S, Charman W N
Department of Optometry and Vision Sciences, University of Manchester Institute of Science and Technology, United Kingdom.
Optom Vis Sci. 1998 Jan;75(1):44-54. doi: 10.1097/00006324-199801000-00024.
The power of a soft contact lens on the eye is a function of its off-eye power, the manner in which the lens flexes on the eye, lens hydration changes, and the corneal topography.
In the present study, we used a high illumination keratometer, which allowed us to obtain front and back surface keratometric readings when the lenses were in position on the eye. The on-eye power of the lens could then be calculated from these readings, with the assumption that the center thickness and refractive index of the lens corresponded to those in vitro.
The estimates of the on-eye powers agreed closely with the results indicated by over-refraction. Moreover, comparison of in vitro with in vivo power estimates indicated that the positive lenses lost power on-eye, whereas the negative ones maintained their power.
The present study confirms the results of earlier workers, who suggested that soft lenses drape to fit the cornea. Our findings appeared to be in agreement with the predictions of most of the models developed in the past.
软性隐形眼镜在眼上的屈光力是其离眼屈光力、镜片在眼上的弯曲方式、镜片水合变化以及角膜地形图的函数。
在本研究中，我们使用了一种高照明角膜曲率计，这使我们能够在镜片位于眼上时获得前表面和后表面的角膜曲率读数。然后，假设镜片的中心厚度和折射率与体外时相对应，便可根据这些读数计算出镜片在眼上的屈光力。
眼上屈光力的估计值与过矫验光结果密切相符。此外，体外与体内屈光力估计值的比较表明，正镜片在眼上会降低屈光力，而负镜片则保持其屈光力。
本研究证实了早期研究者的结果，他们认为软性镜片会贴合角膜。我们的研究结果似乎与过去开发的大多数模型的预测一致。
