如果没有阳光,地球上就没有生气,万物就不能生长。有些疾病就要经常晒太阳,例如老年人易患骨质疏松,经常晒晒太阳对防治该病有益。但阳光照射对健康犹如一把双刃剑,过度会害大于利。紫外线对眼睛晶状体和视网膜的损害很突出,易发生白内障和视网膜黄斑变性。白内障和视网膜病变的发病原因很复杂,但都和光损伤有关。据调查,这 If there is no sunlight, there will be no life on earth, and all things will not grow. Some diseases should always be the sun, such as the elderly susceptible to osteoporosis, often the sun is beneficial to the prevention and treatment of the disease. However, the sun exposure to health is like a double-edged sword, excessive harm will outweigh the benefits. UV damage to the eye lens and the retina is very prominent, prone to cataracts and macular degeneration. The causes of cataracts and retinopathy are complicated, but all are related to light damage. According to the survey, this