Yeung Debby, Sorbara Luigina
School of Optometry and Vision Science University of Waterloo, Waterloo Ontario, Canada (both authors) *
Optom Vis Sci. 2018 Jan;95(1):13-20. doi: 10.1097/OPX.0000000000001164.
It is important to be able to accurately estimate the central corneal clearance when fitting scleral contact lenses. Tools available have intrinsic biases due to the angle of viewing, and therefore an idea of the amount of error in estimation will benefit the fitter.
To compare the accuracy of observers' ability to estimate scleral contact lens central corneal clearance (CCC) with biomicroscopy to measurements using slit-lamp imaging and anterior segment optical coherence tomography (AS-OCT).
In a Web-based survey with images of four scleral lens fits obtained with a slit-lamp video imaging system, participants were asked to estimate the CCC. Responses were compared with known values of CCC of these images determined with an image-processing program (digital CCC) and using the AS-OCT (AS-OCT CCC). Bland-Altman plots and concordance correlation coefficients were used to assess the agreement of CCC measured by the various methods.
Sixty-six participants were categorized for analysis based on the amount of experience with scleral lens fitting into novice, intermediate, or advanced fitters. Comparing the estimated CCC to the digital CCC, all three groups overestimated by an average of +27.3 ± 67.3 μm. The estimated CCC was highly correlated to the digital CCC (0.79, 0.92, and 0.94 for each group, respectively). Compared with the CCC measurements using AS-OCT, the three groups of participants overestimated by +103.3 μm and had high correlations (0.79, 0.93, and 0.94 for each group).
Results from this study validate the ability of contact lens practitioners to observe and estimate the CCC in scleral lens fittings through the use of biomicroscopic viewing. Increasing experience with scleral lens fitting does not improve the correlation with measured CCC from digital or the AS-OCT. However, the intermediate and advanced groups display significantly less inter-observer variability compared with the novice group.
在验配巩膜接触镜时，能够准确估计中央角膜间隙非常重要。现有的工具由于观察角度存在固有偏差，因此了解估计误差的大小将有助于验配人员。
比较观察者通过生物显微镜估计巩膜接触镜中央角膜间隙（CCC）的能力与使用裂隙灯成像和眼前节光学相干断层扫描（AS-OCT）测量结果的准确性。
在一项基于网络的调查中，使用裂隙灯视频成像系统获取了四张巩膜镜验配的图像，要求参与者估计CCC。将参与者的回答与通过图像处理程序确定的这些图像的CCC已知值（数字CCC）以及使用AS-OCT测量的结果（AS-OCT CCC）进行比较。使用 Bland-Altman 图和一致性相关系数来评估各种方法测量的CCC之间的一致性。
66名参与者根据巩膜镜验配经验的多少分为新手、中级或高级验配人员进行分析。将估计的CCC与数字CCC进行比较，所有三组平均高估了+27.3±67.3μm。估计的CCC与数字CCC高度相关（每组分别为0.79、0.92和0.94）。与使用AS-OCT测量的CCC相比，三组参与者高估了+103.3μm，且相关性较高（每组分别为0.79、0.93和0.94）。
本研究结果验证了隐形眼镜从业者通过生物显微镜观察和估计巩膜镜验配中CCC的能力。增加巩膜镜验配经验并不能提高与数字测量或AS-OCT测量的CCC之间的相关性。然而，与新手组相比，中级和高级组的观察者间变异性明显更小。
