Johnson G J
Br J Ophthalmol. 1981 Apr;65(4):270-83. doi: 10.1136/bjo.65.4.270.
To determine the aetiology of spheroidal degeneration of the cornea (Labrador keratopathy), total population surveys were conducted in 5 communities in coastal Labrador and northern Newfoundland. For 4 years records were also kept on all clinic patients aged 40 or more throughout the region. Both methods gave a peak prevalence at latitudes 55 degrees--56 degrees north. The greatest severity and earliest age of onset occurred around the same latitudes. Of the proposed environmental causative agents only ultraviolet radiation, reflected from ice and snow, explains the distribution of the disease. The high cumulative UV dosage is due to the unique geographical and climatic features of the region.
为了确定角膜球状变性（拉布拉多角膜病）的病因，在拉布拉多海岸和纽芬兰北部的5个社区进行了全面的人口调查。同时，对该地区所有40岁及以上的门诊患者进行了为期4年的记录。两种方法均显示，该病在北纬55度至56度之间的患病率最高。病情最严重和发病年龄最早的情况也出现在相同的纬度附近。在所有提出的环境致病因素中，只有冰雪反射的紫外线辐射能够解释该病的分布情况。高累积紫外线剂量是由该地区独特的地理和气候特征造成的。
