Pentacam与IOL Master测量角膜屈光力的比较

目的：比较Scheimpflug 原理摄像系统Pentacam与光学相干生物测量仪IOL Master测量角膜正常的白内障患者角膜屈光力，分析两者的一致性。

方法：前瞻性临床研究。选取我院2017-01/06门诊就诊的角膜正常的白内障患者41例64眼，术前分别采用IOL Master和Pentacam测量角膜屈光力，采集的数据包括：sim K、true net power、角膜中央1.0～7.0mm直径Holladay equivalent K(EKR)(Pentacam)及Km\〖Km=(K1+K2)/2\〗(IOL Master)。两种仪器测量K值之间的差异采用配对样本t检验，其相关性采用Pearson相关性分析，一致性采用Bland-Altman法。

结果：角膜正常的白内障患者Pentacam测量所得true net power、角膜中央1.0、2.0、3.0mm直径EKR 比IOL Master测量所得Km小； 角膜中央4.5、5.0、6.0、7.0mm直径EKR比IOL Master 测量所得Km大，差异具有统计学意义(均P<0.01)。Pentacam测量所得 sim K、角膜中央4.0mm直径EKR与IOL Master测量所得Km差值最小，差值均值分别为-0.03±0.252和0.04±0.244D，差异无统计学意义(t=-1.018，P=0.313； t=1.461，P=0.149)； 且一致性最高，95%一致性界限分别为-0.53～0.46D和-0.43～0.52D。两种仪器间所测量K值均具有较高的相关性(均r>0.9，P<0.01)。

结论：角膜正常的白内障患者Pentacam测量所得sim K、角膜中央4.0mm 直径EKR与IOL Master测量所得Km一致性最高，但使用中需结合临床意义进一步对仪器的适用范围加以判断。

Comparison of corneal power measurements with Pentacam and IOL Master

AIM: To evaluate the agreement and interchangeability of a Scheimpflug camera(Pentacam)and a partial coherence interferometry keratometer(IOL Master)in eyes having preoperative assessment for routine cataract surgery.

METHODS: In this prospective clinical study, 41 patients(64 eyes)with normal cornea from January 2017 to June 2017 in our hospital were enrolled. Simulated K, true net power and Holladay equivalent K(EKR)measured at 1.0 to 7.0 mm corneal diameters were measured by the Pentacam system and mean keratometer(Km)was measured by the IOL Master. Paired samples t test, Pearson correlation analysis and Bland-Altman method were used for statistical analysis.

RESULTS: Among patients with cataract of normal cornea, the mean Scheimpflug K for true net power and EKR at 1.0mm, 2.0mm, 3.0mm corneal diameters were statistically significantly less than the mean Km(IOL Master). The EKR at 4.5mm, 5.0mm, 6.0mm, 7.0mm of corneal diameters were significantly greater than the mean Km(IOL Master)(P<0.01 for all). The difference between Sim K and EKR at 4.0mm measured by Pentacam and Km measured by IOL Master was the smallest(-0.03D±0.252D and 0.04D±0.244D, respectively; t=-1.018, P=0.313; t=1.461, P=0.149), and it had the best uniformity with 95% credible interval of -0.53D to 0.46D(sim K)and -0.43D to 0.52D(equivalent K at 4.0mm). A Pearson correlation revealed a high correlation for corneal power measurements between the two devices(r>0.9 for all, P<0.01 for all).

CONCLUSION: The sim K and EKR at 4.0mm had the closest match with the Km(IOL Master)for Chinese patients with cataract of normal cornea. However, the application of these devices should be combined with clinical features.