It depends on the laws of the country. I believe in the USA it means uncorrectable 20/200 or worse vision. The eye is a remarkably complex organ and thus it ca

It depends on the laws of the country. I believe in the USA it means uncorrectable 20/200 or worse vision. The eye is a remarkably complex organ and thus it can fail in many different ways. There are many people with eye disorders who do not fit the legal definition. Either their condition is correctable (not curable), or their usable vision is above 20/200. Since many conditions are degenerative a person with an eye condition may become legally blind over time.