Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Graefes Arch Clin Exp Ophthalmol. 2013 Nov;251(11):2563-7. doi: 10.1007/s00417-013-2439-8. Epub 2013 Aug 15.
The accuracy of the Holladay 2 (H2) formula is well-documented. This formula requires seven variables to estimate effective lens position (ELP) for the IOL power calculation. The lens thickness (LT) value is one of the required variables. Interestingly, the IOLMaster, which is one of the most commonly used optical biometers, can provide all the required ocular variables except LT value. It has become a pertinent issue to evaluate the accuracy of theH2 formula when it is used without the LT value. The purpose of this study was to evaluate the results when using the H2 formula, without the LT value, and compare such results to those obtained using the Haigis formula and the Hoffer Q formula.
The Institutional review board (IRB) gave their approval for the conduct of this prospective comparative study. One hundred and sixty-three eyes of 143 cataract patients from the Ophthalmology Department, Siriraj Hospital, Thailand were recruited. All eyes were measured using the IOLMaster (Carl Zeiss Meditec, Jena, Germany) for keratometry (K), axial length (AL), anterior chamber depth (ACD), and horizontal white-to-white (WTW) corneal diameter. Then, the LT measurement was obtained by A-scan ultrasonography (Quantel Axis-II, Quantel Medical, USA). Every patient underwent uncomplicated phacoemulsification by a single surgeon (NC) with a single technique using a single IOL model. Post-operative refraction was obtained at 3 months. The mean absolute errors (MAEs), median absolute errors (MedAEs) and percentage of the eyes within ±0.25, ±0.50, and ±1.00 D of predicted refraction was calculated for H2 formula both with and without LT input, Haigis, and Hoffer Q formula. The results were also classified into a group of short AL (<22.0 mm), average AL (22.0 to 24.5 mm) and long AL (>24.5 mm).
There was no statistically significant difference in either MAEs or MedAEs of all formulas in all AL groups including the H2 with and without LT. There was a trend toward lower MAEs and MedAEs for H2 in the long AL group. Percentage of the eyes within ±0.25, ±0.50, and ±1.00 D of predicted refraction were similar in all AL groups.
The preliminary results of this study showed that the H2 formula performed well even without the LT value. It was comparable to the Haigis and Hoffer Q formulas.
Holladay 2（H2）公式的准确性已得到充分证明。该公式需要七个变量来估算 IOL 屈光力计算中的有效透镜位置（ELP）。透镜厚度（LT）值是所需变量之一。有趣的是，IOLMaster 是最常用的光学生物测量仪之一，它可以提供除 LT 值以外的所有所需眼部变量。当不使用 LT 值时，评估 H2 公式的准确性已成为一个重要问题。本研究的目的是评估不使用 LT 值时使用 H2 公式的结果，并将其与 Haigis 公式和 Hoffer Q 公式的结果进行比较。
该研究经 Siriraj 医院机构审查委员会（IRB）批准，为前瞻性比较研究。从泰国 Siriraj 医院眼科招募了 163 只白内障患者的 143 只眼。所有眼睛均使用 IOLMaster（卡尔蔡司医学技术公司，耶拿，德国）进行角膜曲率（K）、眼轴长度（AL）、前房深度（ACD）和水平白到白（WTW）角膜直径测量。然后，通过 A 型超声（美国 Quantel Medical 的 Quantel Axis-II）获取 LT 测量值。每位患者均由同一位外科医生（NC）使用单一技术和单一 IOL 模型进行简单的超声乳化白内障吸除术。术后 3 个月获得术后屈光度数。计算 H2 公式（带和不带 LT 输入）、Haigis 和 Hoffer Q 公式的平均绝对误差（MAE）、中位数绝对误差（MedAE）以及预测屈光度数±0.25、±0.50 和±1.00 D 范围内的眼数百分比。结果还分为短眼轴（<22.0 mm）、平均眼轴（22.0 至 24.5 mm）和长眼轴（>24.5 mm）组。
在所有眼轴组中，包括带和不带 LT 的 H2 公式，所有公式的 MAE 或 MedAE 均无统计学差异。H2 公式在长眼轴组中的 MAE 和 MedAE 有降低的趋势。在所有眼轴组中，预测屈光度数±0.25、±0.50 和±1.00 D 范围内的眼数百分比相似。
本研究的初步结果表明，即使没有 LT 值，H2 公式也能很好地发挥作用。它与 Haigis 和 Hoffer Q 公式相当。
