Department of Ophthalmology, Kanazawa Medical University, Kahoku-gun, Ishikawa 920-0293, Japan.
Eye Contact Lens. 2011 Jul;37(4):191-5. doi: 10.1097/ICL.0b013e31821fbf29.
To assess the validity of the solar ultraviolet index (UVI) as a determiner of eye risk under different conditions of facial profiles and orientation, and reflected light.
Ocular UV radiation (UVR) exposure was measured as a function of the time of the day (solar altitude) using a two-dummy-type mannequin dosimetry system with embedded UVR (260-310 nm) sensors, in September and November in Kanazawa, Japan, on a motorized sun-tracking mount with one dummy face directed toward the sun and the other away from the sun.
A bimodal distribution of UV-B exposure was found in September for the face directed toward the sun, which differed dramatically from the pattern of ambient UVR exposure and measurements taken on the top of the head and those for the eye taken later in the year. Although the overall level was lower, a higher solar altitude is associated with higher UVR exposure in the condition facing away from the sun.
The UVI is based on ambient solar radiation on an unobstructed horizontal plane similar to our measures taken on the top of the head, which differed so much from our measures of ocular exposure that UVI as a determiner of eye risk is deemed invalid. The use of the UVI as an indicator for the need for eye protection can be seriously misleading. Doctors should caution patients with regard to this problem, and eye protection may be warranted throughout the year.
评估太阳紫外线指数 (UVI) 在不同面部轮廓和朝向条件下以及反射光条件下作为眼部风险决定因素的有效性。
在日本金泽市，使用带有嵌入式紫外线辐射 (260-310nm) 传感器的双模拟人型剂量测定系统，在 9 月和 11 月，通过太阳跟踪器的机动装置，将一个模拟人脸朝向太阳，另一个模拟人脸背向太阳，以此作为一天中时间（太阳高度）的函数来测量眼部紫外线辐射暴露情况。
9 月，朝向太阳的脸部出现了紫外线 B 暴露的双峰分布，这与环境紫外线辐射暴露模式以及在头部顶部进行的测量和稍后一年对眼部的测量有显著差异。尽管整体水平较低，但在背向太阳的情况下，更高的太阳高度与更高的紫外线辐射暴露相关。
UVI 是基于无遮挡水平平面上的环境太阳辐射，与我们在头部顶部进行的测量相似，与我们的眼部暴露测量有很大差异，因此，UVI 作为眼部风险的决定因素是无效的。使用 UVI 作为眼部保护需求的指标可能会产生严重的误导。医生应就此问题向患者提出警告，并且可能需要全年佩戴眼部保护装置。
