From the Department of Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany (Langenbucher, Wendelstein); Augen- und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany (Hoffmann); School of Physical Sciences, The Open University, Milton Keynes, United Kingdom (Cayless); Department of Ophthalmology, Johannes Kepler University Linz, Linz, Austria (Wendelstein); Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Aniridia Research, Saarland University, Homburg/Saar, Germany (Szentmáry); Department of Ophthalmology, Semmelweis-University, Budapest, Hungary (Szentmáry).
J Cataract Refract Surg. 2024 Mar 1;50(3):201-208. doi: 10.1097/j.jcrs.0000000000001337.
To investigate the effect of formula constants on predicted refraction and limitations of constant optimization for classical and modern intraocular lens (IOL) power calculation formulae.
Tertiary care center.
Retrospective single-center consecutive case series.
This analysis is based on a dataset of 888 eyes before and after cataract surgery with IOL implantation (Hoya Vivinex). Spherical equivalent refraction predSEQ was predicted using IOLMaster 700 data, IOL power, and formula constants from IOLCon ( https://iolcon.org ). The formula prediction error (PE) was derived as predSEQ minus achieved spherical equivalent refraction for the SRKT, Hoffer Q, Holladay, Haigis, and Castrop formulae. The gradient of predSEQ (gradSEQ) as a measure for the effect of the constants on refraction was calculated and used for constant optimization.
Using initial formula constants, the mean PE was -0.1782 ± 0.4450, -0.1814 ± 0.4159, -0.1702 ± 0.4207, -0.1211 ± 0.3740, and -0.1912 ± 0.3449 diopters (D) for the SRKT, Hoffer Q, Holladay, Haigis, and Castrop formulas, respectively. gradSEQ for all formula constants (except gradSEQ for the Castrop R) decay with axial length because of interaction with the effective lens position (ELP). Constant optimization for a zero mean PE (SD: 0.4410, 0.4307, 0.4272, 0.3742, 0.3436 D) results in a change in the PE trend over axial length in all formulae where the constant acts directly on the ELP.
With IOL power calculation formulae where the constant(s) act directly on the ELP, a change in constant(s) always changes the trend of the PE according to gradSEQ. Formulae where at least 1 constant does not act on the ELP have more flexibility to zero the mean or median PE without coupling with a PE trend error over axial length.
研究公式常数对预测折射的影响，以及经典和现代人工晶状体（IOL）屈光力计算公式常数优化的局限性。
三级护理中心。
回顾性单中心连续病例系列。
本分析基于白内障手术后植入 IOL（豪雅 Vivinex）的 888 只眼的数据集。使用 IOLMaster 700 数据、IOL 功率和 IOLCon（https://iolcon.org）中的公式常数预测预 SEQ 球镜等效折射。公式预测误差（PE）为预测的 SEQ 减去 SRKT、Hoffer Q、Holladay、Haigis 和 Castrop 公式的实际球镜等效折射。作为常数对折射影响的度量，计算了预 SEQ 的梯度（gradSEQ）并用于常数优化。
使用初始公式常数，SRKT、Hoffer Q、Holladay、Haigis 和 Castrop 公式的平均 PE 分别为-0.1782±0.4450、-0.1814±0.4159、-0.1702±0.4207、-0.1211±0.3740 和-0.1912±0.3449 屈光度（D）。除 Castrop R 的 gradSEQ 外，所有公式常数的 gradSEQ 随眼轴长度衰减，因为与有效晶状体位置（ELP）相互作用。为了使平均 PE 为零（SD：0.4410、0.4307、0.4272、0.3742、0.3436 D）进行常数优化，导致所有公式中常数直接作用于 ELP 的 PE 趋势随眼轴长度而变化。
对于常数直接作用于 ELP 的 IOL 屈光力计算公式，常数的变化总是根据 gradSEQ 改变 PE 的趋势。至少有一个常数不作用于 ELP 的公式具有更大的灵活性，可以将平均或中位数 PE 设为零，而不会在眼轴长度上产生 PE 趋势误差。
