Please don' t think like that. You can not call a person with severe myopia a disabled guy, which will definitely make him sad. It is absolutely not a disability, and it is just a detect, you know? In other words, severe myopia is also a kind of nearsightedness, but much worse than common nearsightedness. Besides, people with severe myopia just can' t see things clearly when in a distance but they can still see things nearby. They are not blind, so it is unfair to call them the disabled. I wish you could understand better from my answer.
It depends. Disability use to describe people who cannot function as normal. Even if you have high myopia, as long as it can be corrected by prescription eyeglasses, contact lenses or other methods, you can still see things as most of people do. So, you can continue to work. If so, you are not disability.However, if you have very serious myopia that cause some eye diseases such as retinal detachment and glaucoma etc. it is likely further lead to legal blindness. If this happen, you can apply for disability.