Merriam J C
Trans Am Ophthalmol Soc. 1996;94:803-918.
This thesis explores the idea that light energy, especially ultraviolet light, contributes to the unequal distribution of cataract around the world and to the development of cortical opacities.
In the first section, the thesis reviews historical concepts of the function of the lens and the nature of cataract, epidemiologic data on the global distribution of cataract, and clinical observations of the predominant location of cortical opacification. Second, computer ray tracings and geometric optics demonstrate the passage of light of varying angle of incidence within the lens. Third, two models of the human eye are used to study the refraction of light by the cornea and lens and illustrate the concentration of energy at the equatorial plane of the lens.
Cataract prevalence increases with proximity to the earth's equator, and cortical cataract is most common in the inferior and inferonasal lens. Theoretical studies and the eye models both demonstrate that the concentration of light within the lens increases with angle of incidence, and the eye models suggest that the inferior and inferonasal lens receives significantly more energy than other sections of the lens.
The prevalence of cataract and exposure to ultraviolet energy both increase with decreasing latitude. The most common location of cortical cataract in the inferonasal lens is consistent with the greater dose of light energy received by this portion of the lens. These studies suggest that the global distribution of cataract and the development of cortical cataract are at least in part dependent on the dose of ultraviolet light received by the lens.
本论文探讨光能，尤其是紫外线，导致全球白内障分布不均以及皮质性混浊发展的观点。
在第一部分，论文回顾了晶状体功能和白内障本质的历史概念、全球白内障分布的流行病学数据以及皮质混浊主要位置的临床观察结果。第二，计算机光线追踪和几何光学展示了不同入射角的光线在晶状体内的传播。第三，使用两种人眼模型研究角膜和晶状体对光的折射，并说明晶状体赤道平面处的能量集中情况。
白内障患病率随接近地球赤道而增加，皮质性白内障在晶状体下部和鼻下部分最为常见。理论研究和眼模型均表明，晶状体内的光集中程度随入射角增加，且眼模型表明晶状体下部和鼻下部分比晶状体其他部分接收的能量明显更多。
白内障患病率和紫外线能量暴露均随纬度降低而增加。皮质性白内障最常见于鼻下晶状体的位置与该部分晶状体接收更多光能剂量一致。这些研究表明，白内障的全球分布和皮质性白内障的发展至少部分取决于晶状体接收的紫外线剂量。
