Weschsler S, Wilson G
Am J Optom Physiol Opt. 1978 Feb;55(2):78-83. doi: 10.1097/00006324-197802000-00003.
When a hydrogel lens is placed on the eye, its power may change because of flexing of the lens. The correcting power of the lens when on the eye can be calculated by assuming that the lens flexes to the shape of the underlying cornea. Actual measurements of the correcting power of Hydrocurve lens on the eye were not in agreement with the calculated values. Assuming that the front and back surfaces of the lens flex by the same amount, the presence of a fluid lens between the hydrogel lens and the cornea would account for this discrepancy. For minus lenses of moderate and high power, it was found that the change in power was in the direction of more plus; for low minus and all plus lenses, the change was in the direction of more minus. Under the conditions of the present investigation, correcting power measured with the lens on the eye was in agreement with the calculated value for regular-thickness Hydrocurve lenses of -2.00 D and thin lenses of -0.75 D. This is interpreted to mean that lenses of these powers conform to the shape of the cornea so that the fluid lens is thin and plano. The clinical implications are discussed.
当水凝胶镜片放置在眼睛上时，其屈光度可能会因镜片的弯曲而改变。假设镜片弯曲成下方角膜的形状，就可以计算出其在眼上时的矫正屈光度。Hydrocurve镜片在眼上的实际矫正屈光度测量值与计算值不一致。假设镜片的前表面和后表面弯曲程度相同，那么在水凝胶镜片与角膜之间存在的液性晶状体可以解释这种差异。对于中高度负镜片，发现屈光度的变化方向是向正方向增加；对于低度数负镜片和所有正镜片，变化方向是向负方向增加。在本研究的条件下，在眼上测量的矫正屈光度与-2.00D常规厚度Hydrocurve镜片和-0.75D薄镜片的计算值一致。这被解释为意味着这些屈光度的镜片符合角膜形状，从而使液性晶状体变薄且呈平面状。文中讨论了其临床意义。
