Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Rd, Shanghai, 200031, China.
Eye Institute, Eye and Ear, Nose, and Throat Hospital, Fudan University, Shanghai, China.
Graefes Arch Clin Exp Ophthalmol. 2020 Apr;258(4):795-803. doi: 10.1007/s00417-019-04585-8. Epub 2020 Jan 3.
To compare the accuracy of different corneal astigmatism values measured by Scheimpflug keratometry (Pentacam), including Simulated Keratometry (SimK) and three total corneal astigmatism values, equivalent K reading (EKR), true net power (TNP), and total corneal refractive power (TCRP).
We enrolled 168 eyes of 168 patients with non-toric IOL implantation. Pentacam examination and subjective refraction were performed 3 months after surgery. The agreement, arithmetic difference, and vector difference between refractive astigmatism (RA) and different corneal astigmatism values were compared.
Differences in astigmatism magnitude were significant between SimK and RA in the against-the-rule (ATR) and with-the-rule (WTR) groups but not in total corneal measurements. The meridians of SimK and RA differed significantly in the oblique astigmatism group. The correlations between total corneal astigmatism values and RA were stronger than that between SimK and RA in the total, WTR, and oblique astigmatism groups in Pearson's correlation test. Bland-Altman plots revealed more data points exceeding the limits of agreement (LoA) in SimK measurement in total and WTR subjects. In the ATR group, fewer data points exceeded LoA in EKR. The mean difference vector between SimK and RA was larger than that of other measurements in each astigmatism group. The arithmetic mean of difference vector was significantly smaller in EKR in the total, WTR, and oblique groups.
Among different Pentacam readings, corneal astigmatism measurements considering anterior and posterior corneal surfaces were more representative of total ocular astigmatism than SimK, and EKR showed markedly better performance in astigmatism estimation.
比较 Pentacam 眼前节分析系统（包括模拟角膜曲率计 SimK 和三种总角膜散光值，等效球镜度数 EKR、真实光力 TNP 和总角膜屈光力 TCRP）测量的不同角膜散光值的准确性。
纳入 168 例（168 只眼）接受非散光人工晶状体植入术的患者。术后 3 个月进行 Pentacam 检查和主观验光。比较屈光性散光（RA）与不同角膜散光值的一致性、算术差和向量差。
SimK 与 RA 在逆规散光（ATR）和规则散光（WTR）组的散光大小差异有统计学意义，但在总角膜测量中无差异。在斜轴散光组，SimK 和 RA 的散光子午线有显著差异。Pearson 相关检验显示，在总散光、WTR 和斜轴散光组中，总角膜散光值与 RA 的相关性强于 SimK 与 RA。Bland-Altman 图显示，SimK 测量在总散光和 WTR 受试者中，超出一致性界限（LoA）的数据点更多。在 ATR 组，EKR 测量的 LoA 内数据点更少。SimK 与 RA 的平均差异向量在每个散光组均大于其他测量值。在总散光、WTR 和斜轴散光组中，EKR 的差异向量算术平均值明显更小。
在不同的 Pentacam 读数中，考虑前、后角膜表面的角膜散光测量比 SimK 更能代表总眼散光，EKR 在散光估计方面表现明显更好。
