Bristol Eye Hospital, University Hospitals Bristol NHS Foundation Trust, Lower Maudlin St, Bristol, BS1 2LX, UK.
Sourasky Tel-Aviv Medical Center and the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Graefes Arch Clin Exp Ophthalmol. 2022 Dec;260(12):3889-3895. doi: 10.1007/s00417-022-05729-z. Epub 2022 Jul 1.
Accurate intraocular lens (IOL) calculation in subjects with irregular astigmatism is challenging. This study evaluated the accuracy of using Scheimpflug-derived central 2-mm equivalent keratometry reading (EKR) values for IOL calculation in irregular astigmatism.
This retrospective study included subjects (31 eyes of 30 patients) who underwent cataract surgery and IOL calculation using the 2-mm central EKR methods. We compared prediction error (PE) and absolute PE (APE) outcomes using SRK/T and Barrett Universal II formulas for keratometry data obtained from the IOLMaster 500 and Pentacam (anterior corneal sim k) devices.
Cataract surgery and IOL calculation using the 2-mm central EKR methods resulted in improved visual acuity (uncorrected: from 1.13 ± 0.38 to 0.65 ± 0.46 logMar, p < 0.01; best-corrected: from 0.45 ± 0.24 to 0.26 ± 0.20 logMar, p < 0.01) after surgery. The percentage of subjects with best-corrected visual acuity of 6/6 was 22%, < 6/9 was 58%, and < 6/12 was 71%. For both the SRK/T and the Barrett formulas, the PE was similar to those obtained by IOLMaster (> 0.14) but lower than those obtained by the anterior corneal sim k (p < 0.02). IOLMaster provided keratometry reading in only 23/31 (74.1%) of cases.
The use of Scheimpflug central 2-mm EKR for IOL calculation in irregular astigmatism was beneficial in terms of visual acuity improvement. It had comparable refractive prediction performance to the IOLMaster 500 and better than the anterior corneal sim K. The 2-mm EKR method can be used when IOLMaster cannot provide a reliable reading in abnormal corneas.
在不规则散光患者中准确计算人工晶状体（IOL）具有挑战性。本研究评估了使用 Scheimpflug 衍生的中央 2mm 等效角膜曲率读数（EKR）值进行 IOL 计算在不规则散光中的准确性。
本回顾性研究纳入了 30 例患者（31 只眼），这些患者接受了白内障手术和 IOL 计算，使用 2mm 中央 EKR 方法。我们比较了使用 IOLMaster 500 和 Pentacam（前角膜模拟 k）设备获得的角膜曲率数据，SRK/T 和 Barrett Universal II 公式的预测误差（PE）和绝对 PE（APE）结果。
使用 2mm 中央 EKR 方法进行白内障手术和 IOL 计算可改善视力（未矫正：从 1.13±0.38 提高至 0.65±0.46 logMar，p<0.01；最佳矫正：从 0.45±0.24 提高至 0.26±0.20 logMar，p<0.01）。术后最佳矫正视力为 6/6 的患者比例为 22%，<6/9 的比例为 58%，<6/12 的比例为 71%。对于 SRK/T 和 Barrett 公式，PE 与 IOLMaster 获得的值相似（>0.14），但低于前角膜模拟 k 获得的值（p<0.02）。IOLMaster 仅在 23/31（74.1%）例中提供了角膜曲率读数。
在不规则散光中使用 Scheimpflug 中央 2mm EKR 进行 IOL 计算在提高视力方面是有益的。它的屈光预测性能与 IOLMaster 500 相当，优于前角膜模拟 K。当 IOLMaster 无法在前异常角膜中提供可靠读数时，可以使用 2mm EKR 方法。
