Iwami S, Senoh K
Department of Ophthalmology, Iwate Prefectural Kitakami Hospital, 3-15-36 Kunenbashi, Kitakami 024-0063, Japan.
Nippon Ganka Gakkai Zasshi. 2001 Mar;105(3):155-60.
To understand the effect of the error in corneal refractive power on the optically calculated axial length (AXO) and the postoperative predicted refraction (Q'gl) calculated from the aphakic refraction (Qaph).
We used the Gullstrand's schematic eye, in which the intraocular lens (+20 D) was inserted at a depth of 5 mm, and calculated Qaph and postoperative refraction (Qgl) geometrically when the corneal radius of the anterior surface (Rfc) changed from 7 mm to 9 mm. AXO was calculated using the calculation formula from a previous report, and then Q'gl was calculated from the AXO and the true axial length (AXT) using the theoretical calculation formula (regarding the fictitious corneal refractive index as 1.3315).
When the measured corneal radius of the anterior surface (K) was equal to Rfc, the error of the AXO was largest (AXO/AXT = 101.512) when K was 9 mm. The error in power prediction (Qgl-Q'gl) of the AXT was 7.7 times larger than that of AXO.
If K is exact, AXO is useful to predict the intraocular lens depth because the error of AXO is small. The error in power prediction of AXO is smaller than that of AXT.
了解角膜屈光力误差对光学计算眼轴长度（AXO）以及根据无晶状体眼屈光不正（Qaph）计算的术后预测屈光不正（Q'gl）的影响。
我们使用了Gullstrand简化眼模型，其中人工晶状体（+20 D）植入深度为5 mm，当前表面角膜半径（Rfc）从7 mm变化到9 mm时，通过几何方法计算Qaph和术后屈光不正（Qgl）。使用先前报告中的计算公式计算AXO，然后使用理论计算公式（将虚拟角膜折射率视为1.3315）从AXO和真实眼轴长度（AXT）计算Q'gl。
当前表面测量的角膜半径（K）等于Rfc时，当K为9 mm时AXO的误差最大（AXO/AXT = 101.512）。AXT的屈光力预测误差（Qgl - Q'gl）比AXO的大7.7倍。
如果K准确，AXO可用于预测人工晶状体植入深度，因为AXO的误差较小。AXO的屈光力预测误差小于AXT的。
