Legally blindness refers to one has central visual acuity of 20/200 or less even if he wears a correcting lens. There are a variety of causes to account for legally blindness, among which the most common causes are cataracts, glaucoma, macular degeneration, corneal opacity, diabetic retinopathy, trachoma, children blindness and onchocerciasis.
Well, nowadays, there are more and more people who have suffered the legal blindness. First, you should know that legal blindness means a person has a vision that is 20/200 in a person's best eye with correction. When you are legally blindness, the visual field is limited to less than 20 degrees. And there are many reasons which can lead to it, such as alcohol drinking, smoking, even some medical drugs. According to some researches, legal blindness does not mean that a person cannot see at all. People who are legally blind often have some vision, but their field of vision may be very narrow or blurry. Of course, people who are legally blindness can wear contact lenses to see clearly.