J Refract Surg. 2021 May;37(5):312-317. doi: 10.3928/1081597X-20210222-03. Epub 2021 May 1.
To compare different new-generation biometric formulas and ray-tracing for small-aperture intraocular lens (IOL) (IC-8; Acufocus, Inc) implantation in patients undergoing cataract and refractive lens exchange surgery with highly irregular corneas.
This monocenter study included 17 eyes of 17 patients with highly irregular corneas of different genesis. Biometric and topographic corneal data were assessed using the IOLMaster 700 (Carl Zeiss Meditec) and Pentacam (Oculus Optkigeräte GmbH). Prediction and absolute error were compared after 3 months based on manifest refraction. Furthermore, change of total corneal refractive power in different corneal pathologies was also evaluated. For IOL power calculation, three fourth-generation IOL formulas were compared (Haigis, SRK-T, and Barrett Universal II). The dataset was then checked against ray-tracing and analyzed to improve prediction error in these highly irregular corneas.
All patients showed an improvement in visual acuity postoperatively with a mean spherical equivalent of -1.22 ± 0.49 diopters (D). Overall comparison of the three formulas showed the Haigis formula to be superior in terms of the smallest deviation of predictive and absolute error. IOL calculations with ray-tracing were possible in all eyes, but showed inaccurate results with keratometric values of 48.00 D and greater.
The IC-8 IOL is well suited for patients with lens exchange in highly irregular corneas. The Haigis formula seemed to be the most accurate in the patient group. Ray-tracing confirmed the results of biometric formulas up to a keratometric value of 48.00 D and should be compared with standard biometric formulas to address corneal irregularities and to minimize refractive surprises after surgery. A comparison with ray-tracing in eyes with a keratometric value of greater than 48.00 D should not be considered due to the inaccurate results. .
比较不同新一代生物测量公式和光线追踪在白内障和屈光性晶状体置换手术中用于小切口人工晶状体（IOL）（IC-8；Acufocus，Inc）植入的效果，这些手术患者的角膜具有不同的高度不规则性。
这项单中心研究纳入了 17 名角膜高度不规则的不同病因的患者的 17 只眼。使用 IOLMaster 700（卡尔蔡司医学系统）和 Pentacam（Oculus Optkigeräte GmbH）评估生物测量和角膜地形图数据。基于主觉验光，在术后 3 个月比较预测值和绝对误差。此外，还评估了不同角膜病变下总角膜屈光力的变化。对于 IOL 度数计算，比较了三种第四代 IOL 公式（Haigis、SRK-T 和 Barrett Universal II）。然后，根据光线追踪检查数据集并进行分析，以改善这些高度不规则角膜的预测误差。
所有患者术后视力均有改善，平均等效球镜度为-1.22 ± 0.49 屈光度（D）。三种公式的总体比较表明，Haigis 公式在预测误差和绝对误差的最小偏差方面表现更好。所有眼睛都可以进行 IOL 计算的光线追踪，但角膜曲率值为 48.00 D 及以上时，结果不准确。
IC-8 IOL 非常适合在高度不规则角膜中进行晶状体置换的患者。Haigis 公式在患者组中似乎最准确。光线追踪证实了生物测量公式的结果，直至角膜曲率值为 48.00 D，应与标准生物测量公式进行比较，以解决角膜不规则性，并尽量减少术后的屈光意外。由于结果不准确，不应考虑与光线追踪在角膜曲率值大于 48.00 D 的眼睛进行比较。
