School of Medicine, University of New South Wales, Kensington, NSW, Australia.
Brien Holden Vision Institute Limited, Kensington, Australia.
Cornea. 2020 Sep;39(9):1157-1163. doi: 10.1097/ICO.0000000000002322.
A clinical examination technique to detect pathology within the anterior eye is known as "sclerotic scatter" (SS). Its propagation pathway has not been thoroughly investigated. Although conventionally theorized to occur by "total internal reflection" (TIR) within the cornea, existing data suggest that this may be an incomplete explanation.
An anterior eye model representative of a human eye has been constructed using nonsequential ray tracing (OpticStudio 18.1). Three generations of the model were constructed to support the analyses of the pathway of light in SS. A design of experiment methodology involving the key parameters was used to determine the slit-lamp setup for optimum clinical visualization.
Most of the light directed into the temporal limbus in SS is lost (52%) into the sclera or reemitted back to the clinician. Only 0.006% of light that transits the central cornea undergoes TIR off the anterior cornea and more significantly 0.000125% off the posterior cornea. The optimal slit-lamp setup parameters to maximize the clinician's visualization are also summarized.
The propagation of light within SS primarily does not occur by TIR off the posterior cornea but rather the direct transcameral propagation of light. SS also represents an inefficient usage of light, with approximately half of the light creating a potential glare source for clinicians. We have formulated a recommended set of parameters for the slit-lamp setup to maximize clinical visualization. We also describe the transcameral pathways involved in SS that create a corneal "backlighting" effect. Almost a century after Graves original description, the optics of this phenomenon are described here.
一种用于检测眼前部病变的临床检查技术称为“巩膜散射”（SS）。其传播途径尚未得到彻底研究。尽管传统上认为它是在角膜内通过“全内反射”（TIR）发生的，但现有数据表明，这可能只是一个不完全的解释。
使用非序列光线追踪（OpticStudio 18.1）构建了一个具有代表性的人眼前部模型。构建了三代模型以支持 SS 中光传播途径的分析。使用涉及关键参数的实验设计方法来确定最佳临床可视化的裂隙灯设置。
在 SS 中引导到颞侧角膜缘的大部分光（52%）丢失在巩膜中或重新发射回临床医生。只有 0.006%穿过中央角膜的光在角膜前发生 TIR，更重要的是，0.000125%在角膜后发生 TIR。还总结了最大化临床医生可视化效果的最佳裂隙灯设置参数。
SS 中光的传播主要不是通过后角膜的 TIR 发生，而是光的直接穿通传播。SS 还代表了光的低效利用，大约一半的光为临床医生创造了潜在的眩光源。我们已经制定了一套推荐的裂隙灯设置参数，以最大限度地提高临床可视化效果。我们还描述了 SS 中涉及的穿通途径，这些途径会产生角膜“背面照明”效果。在 Graves 最初描述近一个世纪后，这里描述了这种现象的光学原理。
