Corneal confocal microscopy is a rapid reproducible ophthalmic technique for quantifying corneal nerve abnormalities

PurposeTo assess the effect of applying a protocol for image selection and the number of images required for adequate quantification of corneal nerve pathology using in vivo corneal confocal microscopy (IVCCM).MethodsIVCCM was performed in 35 participants by a single examiner. For each participant, 4 observers used a standardized protocol to select 6 central corneal nerve images to assess the inter-observer variability. Furthermore, images were selected by a single observer on two occasions to assess intra-observer variability and the effect of sample size was assessed by comparing 6 with 12 images. Corneal nerve fiber density (CNFD), branch density (CNBD) and length (CNFL) were quantified using fully automated software. The data were compared using the intra class correlation coefficient (ICC) and Bland-Altman agreement plots for all experiments.ResultsThe ICC values for CNFD, CNBD and CNFL were 0.93 (PConclusionsThis study shows that implementing a standardized protocol to select IVCCM images results in high intra and inter-observer reproducibility for all corneal nerve parameters and 6 images are adequate for analysis. IVCCM could therefore be deployed in large multicenter clinical trials with confidence.

【研究目的】本研究旨在评估图像选取方案的应用效果，以及采用活体角膜共聚焦显微镜（in vivo corneal confocal microscopy, IVCCM）对角膜神经病变进行充分量化分析所需的图像数量。【研究方法】本研究由1名检查者对35名受试者实施活体角膜共聚焦显微镜（in vivo corneal confocal microscopy, IVCCM）检测。针对每名受试者，4名观察者采用标准化方案选取6张中央角膜神经图像，以评估观察者间变异；此外，由同一名观察者在两次不同时段选取图像，以评估观察者内变异；同时通过对比6张与12张图像的分析结果，评估图像样本量的影响。采用全自动分析软件对角膜神经纤维密度（corneal nerve fiber density, CNFD）、分支密度（branch density, CNBD）及神经纤维长度（length, CNFL）进行量化分析。所有实验均采用组内相关系数（intra class correlation coefficient, ICC）与Bland-Altman一致性图对数据进行比较分析。【研究结果】角膜神经纤维密度（CNFD）、分支密度（CNBD）及神经纤维长度（CNFL）的组内相关系数（ICC）值均为0.93（P【研究结论】本研究表明，采用标准化方案选取IVCCM图像，可使所有角膜神经参数均具备较高的观察者内与观察者间重现性，且6张图像即可满足分析需求。因此，IVCCM可放心应用于大型多中心临床试验。