Holladay J T, Maverick K J
University of Texas Medical School, Houston, USA.
Am J Ophthalmol. 1998 Sep;126(3):339-47. doi: 10.1016/s0002-9394(98)00088-9.
To theoretically derive and empirically validate the relationship between the actual thick intraocular lens and the thin lens equivalent.
Included in the study were 12 consecutive adult patients ranging in age from 54 to 84 years (mean +/- SD, 73.5 +/- 9.4 years) with best-corrected visual acuity better than 20/40 in each eye. Each patient had bilateral intraocular lens implants of the same style, placed in the same location (bag or sulcus) by the same surgeon. Preoperatively, axial length, keratometry, refraction, and vertex distance were measured. Postoperatively, keratometry, refraction, vertex distance, and the distance from the vertex of the cornea to the anterior vertex of the intraocular lens (AV(PC1)) were measured. Alternatively, the distance (AV(PC1)) was then back-calculated from the vergence formula used for intraocular lens power calculations.
The average (+/-SD) of the absolute difference in the two methods was 0.23 +/- 0.18 mm, which would translate to approximately 0.46 diopters. There was no statistical difference between the measured and calculated values; the Pearson product-moment correlation coefficient from linear regression was 0.85 (r2 = .72, F = 56). The average intereye difference was -0.030 mm (SD, 0.141 mm; SEM, 0.043 mm) using the measurement method and +0.124 mm (SD, 0.412 mm; SEM, 0.124 mm) using the calculation method.
The relationship between the actual thick intraocular lens and the thin lens equivalent has been determined theoretically and demonstrated empirically. This validation provides the manufacturer and surgeon additional confidence and utility for lens constants used in intraocular lens power calculations.
从理论上推导并通过实验验证实际厚人工晶状体与等效薄晶状体之间的关系。
本研究纳入了12例连续的成年患者，年龄在54至84岁之间（平均±标准差，73.5±9.4岁），每只眼睛的最佳矫正视力均优于20/40。每位患者均由同一位外科医生在相同位置（囊袋或睫状沟）植入了双侧相同型号的人工晶状体。术前测量眼轴长度、角膜曲率、屈光度数和顶点距离。术后测量角膜曲率、屈光度数、顶点距离以及从角膜顶点到人工晶状体前顶点的距离（AV(PC1)）。或者，然后根据用于人工晶状体屈光度计算的聚散度公式反推距离（AV(PC1)）。
两种方法的绝对差值的平均值（±标准差）为0.23±0.18毫米，这相当于约0.46屈光度。测量值与计算值之间无统计学差异；线性回归的Pearson积矩相关系数为0.85（r2 = 0.72，F = 56）。使用测量方法时，双眼平均差值为-0.030毫米（标准差，0.141毫米；标准误，0.043毫米），使用计算方法时为+0.124毫米（标准差，0.412毫米；标准误，0.124毫米）。
已从理论上确定并通过实验证明了实际厚人工晶状体与等效薄晶状体之间的关系。这一验证为人工晶状体屈光度计算中使用的晶状体常数的制造商和外科医生提供了额外的信心和实用性。
