NTA follows the Persons with Benchmark Disabilities Act for PWD reservation for JEE. According to the Information Bulletin,  Blindness and low vision are considered as one of the parameters for securing reservation under PWD quota. The disability range should be 40% or more. While we cannot assess the percentage of visual impairment, you need to visit a District Medical Hospital for a PWD certificate. They will assess you and decide the range of visual impairment.