Choi Hyuk Jin, Lee Sang-Mok, Lee Ja Young, Lee Seung Yong, Kim Mee Kum, Wee Won Ryang
*MD, PhD †MD Department of Ophthalmology, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Republic of Korea (HJC); Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea (HJC, S-ML, MKK, WRW); Department of Ophthalmology, Incheon Medical Center, Incheon, Republic of Korea (JYL); and Department of Ophthalmology, Eulji University Hospital, Daejeon, Republic of Korea (SYL).
Optom Vis Sci. 2014 Jul;91(7):793-802. doi: 10.1097/OPX.0000000000000298.
To investigate and validate methods for measuring the radius of anterior scleral curvature using anterior segment optical coherence tomography images.
Twenty-four volunteers were enrolled in this study. Anterior segment optical coherence tomography images, centered on horizontal/vertical limbus, including adjacent anterior sclera, were obtained in addition to conventional images centered on the optical axis. Central horizontal, nasal, and temporal optical coherence tomography images were consolidated to a new image for subsequent analyses. The reference points of limbal surface and three scleral points were marked nasally and temporally. The radius of a best-fit circle to the six scleral points was derived (the BFC [best-fit circle] method) and the radii of two circles, the centers of which are on the optical axis and pass through the points of the scleral surface at 2 mm from the limbus nasally and temporally, were calculated (the axial method). To assess the reliability and accuracy of each method, intraobserver and interobserver agreements were analyzed and the radii of contact lenses with known curvatures were measured.
The mean (±SD) radius of a BFC was 13.12 (±0.80) mm. The mean (±SD) radius of nasal anterior scleral curvature (13.33 ± 1.12 mm) was significantly greater than that of temporal anterior scleral curvature (12.32 ± 0.77 mm) (paired samples t test, p < 0.001). The BFC and axial methods showed excellent intraobserver and interobserver agreements for measurements (intraclass correlation coefficient > 0.75, p < 0.001), whereas both methods showed a tendency to slightly underestimate the actual curvature of a rigid contact lens of known dimensions (-0.07 ± 0.13 mm [the BFC method] and -0.19 ± 0.07 mm [the axial method], Wilcoxon signed rank test, p = 0.173 and p = 0.028, respectively).
Anterior segment optical coherence tomography is a valuable tool for measuring the radii of anterior scleral curvatures by image processing and mathematical calculation and can provide useful information in specific clinical situations such as designing scleral lenses.
研究并验证使用眼前节光学相干断层扫描图像测量前巩膜曲率半径的方法。
本研究纳入了24名志愿者。除了以光轴为中心的传统图像外，还获取了以水平/垂直角膜缘为中心、包括相邻前巩膜的眼前节光学相干断层扫描图像。将中央水平、鼻侧和颞侧的光学相干断层扫描图像合并为一张新图像用于后续分析。在鼻侧和颞侧标记角膜缘表面的参考点和三个巩膜点。得出与六个巩膜点拟合最佳的圆的半径（最佳拟合圆[BFC]法），并计算两个圆的半径，这两个圆的圆心在光轴上，且经过鼻侧和颞侧距角膜缘2mm处的巩膜表面点（轴向法）。为评估每种方法的可靠性和准确性，分析了观察者内和观察者间的一致性，并测量了已知曲率的隐形眼镜的半径。
BFC的平均（±标准差）半径为13.12（±0.80）mm。鼻侧前巩膜曲率的平均（±标准差）半径（13.33±1.12mm）显著大于颞侧前巩膜曲率的平均（±标准差）半径（12.32±0.77mm）（配对样本t检验，p<0.001）。BFC法和轴向法在测量中显示出极好的观察者内和观察者间一致性（组内相关系数>0.75，p<0.001），而两种方法均显示出略微低估已知尺寸硬性隐形眼镜实际曲率的趋势（BFC法为-0.07±0.13mm，轴向法为-0.19±0.07mm，Wilcoxon符号秩检验，p分别为0.173和0.028）。
眼前节光学相干断层扫描是一种通过图像处理和数学计算测量前巩膜曲率半径的有价值工具，并且在诸如设计巩膜镜片等特定临床情况下可提供有用信息。
