Glasses can be divided into several virieties, according to their own applications, such as reading glasses usually for aged people, myopic glasses for nearsighted people, hypermetropic glasses for farsighted people, sunglasses to screen off the ultraviolet rays, and so on and so forth. As long as you wear the right kind of glasses according to your personal condition, and as long as you wear them in a correct way, glasses can not do much harm to eyes, instead, they can protect the eyes or help correct the prescription of the eyes. On the other hand, cataracts are the result of degeneration and muddy condition of the crystalline lenses. There are some factors for cataracts. First of all, it can be that the eyes have been excessively exposed to the ultraviolet rays, which is quite easily to cause the lesion of crystalline lenses. Secondly, as time goes by and the age of people increases, the deposits of wastes accumulated in the crystalline lenses are finally able to completely impede the vision, thus making people cannot see and become blind because of cataracts, which usually happens among the group of aged people. Thirdly, nowadays too much work and high pressure can also cause to cataracts, which makes cataracts more frequently seen among young people. In addition, trauma, malnutrition and poisoning can also cause cataracts.
