Background Accurate measurement of corneal refractive parameters plays an important role in the diagnosis of eye diseases,design of refractive surgery and calculation of intraocular lens (IOL) power.Ophtha TOP is a new IOL calculator,so it is necessary to evaluate the repeatability and accuracy of Ophtha TOP in measuring corneal refractive parameters.Objective This study was to evaluate the repeatability of Ophtha TOP in measuring corneal refractive status in normal eyes and determine the agreement of the measuring outcomes between Ophtha TOP and Pentacam in pre-surgery cataract eyes.Methods A reliability evaluation method of diagnosis test was performed from September 2013 to October 2014.Sixty eyes of healthy volunteers aged (30.83 ±8.66) years old were examined in Tianjin Eye Hospital with Ophtha TOP for more than 5 times to evaluate the stability in measuring corneal refractive parameters.Corneal refractive parameters were measured by both Ophtha TOP and Pentacam for more than twice in 30 pre-surgery cataract eyes to assess the agreement with Pentacam.Keratometry and astigmatism parameters were recorded,including the flattest meridian (Kf),steepest meridian (Ks),mean keratometry (Km) and the astigmatism at J0 and J45.Intra-class correlation coefficients (ICC),repeatability (2.77Sw) and coefficient of variation (CoVs) were used to assess the stability of Ophtha TOP,and Bland-Altman graphs were adopted to value the consistency of measuring outcomes between Ophtha TOP and Pentacam.This study complied with Helsinki declaration,and written informed consent was obtained from each patient prior to any medical examination.Results The ICC of Ks,Kf,Km,J0 and J45 by Ophtha TOP were all ≥0.90,and 2.77Sw were all ≤0.36,The CoVs of Kf,Ks,Km by Ophtha TOP were all ≤0.30.The measuring values of Kf,Ks and Km were significantly higher in the Ophtha TOP than those in the Pentacam,with the mean differences (0.18±0.28) D,(0.24±0.29) D and (0.21± 0.26) D,respectively(t =3.48,4.50,4.49,all at P=0.00).The mean difference of the J0 was (0.07±0.21) D and that of the J45 was (-0.02±0.18)D between Ophtha TOP and Pentacam,showing insignificant differences between them (both at P＞0.05).Bland-Altman graphs revealed that the 95％ limit of agreement (LoA) of Kf,Ks and Km between the two methods was-0.37 D to 0.73 D,-0.33 D to 0.81 D and-0.30 D to 0.72 D,respectively,and that of J0 and J45 was-0.34 D to 0.48 D and-0.37 D to 0.33 D,respectively.Conclusions Ophtha TOP shows an excellent repeatability.Compared with Pentacam,Ophtha TOP presents a good consistence for measurement of the corneal astigmatism and moderate consistence for corneal curvature.%背景 角膜屈光参数的准确测量对于眼表疾病的诊治、屈光手术的设计、人工晶状体屈光度的计算等至关重要,Ophtha TOP是一种用于临床的新型角膜人工晶状体测量仪,但验证其测量角膜屈光参数稳定性及准确性的研究尚少见. 目的 评估Ophtha TOP测量正常人群角膜屈光参数的稳定性,并评价白内障术前患者用Ophtha TOP测量的角膜屈光参数与Pentacam测量结果的一致性. 方法 采用诊断试验可靠性评价方法,2013年9月至2014年10月在天津市眼科医院选取健康志愿者30人60眼行Ophtha TOP检查,评价Ophtha TOP测量角膜屈光参数的稳定性;另选取拟行白内障手术的白内障患者30例30眼进行OphthaTOP检查,以评估Ophtha TOP测量角膜屈光参数与Pentacam测量结果的一致性.记录角膜曲率最平坦曲率径线(Kf)、最陡峭曲率径线(Ks)、平均角膜曲率(Km),并记录轴位J0和J45的散光度.正常眼使用OphthaTOP连续测量5次以上,采用组内相关系数(ICC)、变异系数(CoYs)和重复度(2.77Sw)评价Ophtha TOP测量上述参数的稳定性;白内障患者用Ophtha TOP和Pentacam连续测量2次以上,采用Bland-Altman一致性分析法评估Ophtha TOP测量的角膜屈光参数和散光参数与Pentacam测量结果的一致性. 结果 Ophtha TOP测量的正常眼Kf、Ks、Km、J0和J45的ICC均≥0.90,重复度2.77Sw均≤0.36,Kf、Ks、Km的CoVs均≤0.30.Ophtha TOP与Pentacam测量的白内障眼的角膜屈光参数Kf、Ks和Km的平均差值分别为(0.18±0.28)、(0.24±0.29)和(0.21±0.26)D,Ophtha TOP测量值均略高于Pentacam测量值,差异均有统计学意义(t=3.48、4.50、4.49,均P=0.00);而2种测量仪器测量的散光参数J0、J45的平均差值分别为(0.07±0.21)D和(-0.02±0.18)D,差异均无统计学意义(均P＞0.05).Bland-Altman一致性检验显示,2种测定方法测量的Kf、Ks和Km的95％一致性区间(LoA)分别为-0.37 ～0.73、-0.33～0.81和-0.30 ～0.72 D,J0和J45的95％LoA分别为-0.34～0.48和-0.37～0.33D. 结论 Ophtha TOP对正常人眼角膜屈光参数测量结果的稳定性较好.在白内障术前患者中,Ophtha TOP测量的角膜曲率和角膜散光结果与Pentacam测量值一致性好.
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