A novel method to locate the centre of keratoconus (KC) and the transition zone between the pathological area and the rest of the corneal tissue is proposed in this study. A spherical coordinate system was used to generate a spherical height map measured relative to the centre of the optimal sphere fit, and normal to the surface. The cone centre was defined as the point with the maximum height. Second derivatives of spherical height were then used to estimate the area of pathology in an iterative process. There was mirror symmetry between cone centre locations in both eyes. The mean distance between cone centre and corneal apex was 1.45 ± 0.25 mm (0.07–2.00), the mean cone height normal to the surface was 37 ± 23 µm (2–129) and 75 ± 45 µm (5–243) in the anterior and posterior surfaces, respectively. There was a significant negative correlation between the cone height and the radius of the sphere of optimal fit (p < 0.05 for both anterior and posterior surfaces). On average, posterior cone height was larger than the corresponding anterior cone height by 37 ± 24 µm (0–158). The novel method proposed can be used to estimate the cone centre and area, and explore the changes in anterior and posterior corneal surfaces that take place with KC progression. It can help improve understanding of keratoconic corneal morphology and assist in developing customized treatments.

中文翻译：

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圆锥角膜中锥体大小和中心的表征

本研究提出了一种定位圆锥角膜 (KC) 中心和病理区域与其余角膜组织之间的过渡区的新方法。球坐标系用于生成相对于最佳球体拟合中心和表面法线测量的球面高度图。锥体中心被定义为具有最大高度的点。然后使用球高的二阶导数来估计迭代过程中的病理区域。双眼锥体中心位置呈镜像对称。锥体中心和角膜顶点之间的平均距离为 1.45 ± 0.25 mm (0.07–2.00)，垂直于表面的平均锥体高度为 37 ± 23 µm (2–129) 和 75 ± 45 µm (5–243)分别是前表面和后表面。圆锥高度与最佳拟合球体的半径之间存在显着的负相关（前表面和后表面的 p < 0.05）。平均而言，后锥高度比相应的前锥高度大 37 ± 24 µm (0–158)。所提出的新方法可用于估计锥体中心和面积，并探索随着 KC 进展而发生的前后角膜表面的变化。它可以帮助提高对圆锥角膜形态的理解，并有助于开发定制的治疗方法。所提出的新方法可用于估计锥体中心和面积，并探索随着 KC 进展而发生的前后角膜表面的变化。它可以帮助提高对圆锥角膜形态的理解，并有助于开发定制的治疗方法。所提出的新方法可用于估计锥体中心和面积，并探索随着 KC 进展而发生的前后角膜表面的变化。它可以帮助提高对圆锥角膜形态的理解，并有助于开发定制的治疗方法。