Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
J Refract Surg. 2012 Oct;28(10):714-24. doi: 10.3928/1081597X-20120921-07.
To investigate the predictability of various intraocular lens (IOL) power calculation methods in granular corneal dystrophy type 2 (GCD2) with prior phototherapeutic keratectomy (PTK) and to suggest the more predictable IOL power calculation method.
Medical records of 20 eyes from 16 patients with GCD2, all having undergone cataract surgery after PTK, were retrospectively evaluated. Postoperative cataract refractive errors were compared with target diopters (D) using IOL power calculation methods as follows: 1) myopic and 2) hyperopic Haigis-L formula in IOLMaster (Carl Zeiss Meditec); 3) SRK/T formula using 4.5-mm zone Holladay equivalent keratometry readings (EKRs) (single-K Holladay EKRs method); 4) central keratometry power of true net power map in the Pentacam system (Oculus Optikgeräte GmbH); and 5) clinical history, Aramberri double-K, and double-K Holladay EKRs methods. Topographic status of corneal curvature after PTK was evaluated.
Fourteen (70%) of 20 eyes showed central island formation after PTK. When central island was present, the mean absolute error (MAE) using the hyperopic Haigis-L formula was 0.25±0.15 D. When central island was not present, the myopic Haigis-L formula showed MAE of 0.33±0.16 D. When central island formation and IOLMaster keratometry underestimation were present, the hyperopic Haigis-L formula showed the least MAE of 0.26±0.08 D when switching the IOL-Master keratometry values equal to 4.5-mm zone Holladay EKRs.
In planning for cataract surgery after PTK in GCD2, topographic analysis for central island formation is necessary. With or without central island formation, the hyperopic or myopic Haigis-L formula can be applied. When IOLMaster keratometry shows underestimation, the Haigis-L formula using 4.5-mm zone Holladay EKRs can be considered.
研究先前行光动力疗法（PTK）的 2 型颗粒状角膜营养不良（GCD2）患者各种人工晶状体（IOL）计算公式的预测性，并提出更具预测性的 IOL 计算公式。
回顾性分析 16 例 20 只眼 GCD2 患者的病历资料，所有患者均在 PTK 后行白内障手术。采用如下 IOL 计算公式比较术后白内障屈光不正与目标屈光度（D）的差异：1）近视和 2）远视 Haigis-L 公式（IOLMaster，卡尔蔡司）；3）使用 4.5mm 区 Holladay 等效角膜曲率读数（EKR）的 SRK/T 公式（单 K Holladay EKR 法）；4）Pentacam 系统中的中央角膜真实净力图的角膜曲率力（Oculus Optikgeräte GmbH）；5）临床病史、Aramberri 双 K 和双 K Holladay EKR 法。评估 PTK 后角膜曲率的地形状态。
20 只眼中 14 只（70%）出现 PTK 后中央岛形成。当存在中央岛时，远视 Haigis-L 公式的平均绝对误差（MAE）为 0.25±0.15 D。当不存在中央岛时，近视 Haigis-L 公式的 MAE 为 0.33±0.16 D。当存在中央岛形成和 IOLMaster 角膜曲率低估时，当将 IOL-Master 角膜曲率值切换为 4.5mm 区 Holladay EKR 时，远视 Haigis-L 公式显示出最小的 MAE 为 0.26±0.08 D。
在 GCD2 患者 PTK 后行白内障手术时，需要进行中央岛形成的地形分析。无论是否存在中央岛形成，都可以应用远视或近视 Haigis-L 公式。当 IOLMaster 角膜曲率显示低估时，可以考虑使用 4.5mm 区 Holladay EKR 的 Haigis-L 公式。
