Dear Ravinder, AIIMS New Delhi reserves 3% of total seats for Orthopedic Physically Handicapped on horizontal basis. For claiming reservation, the disability to be considered is of lower limbs between 50%-70%. If such candidates are not available, the candidates with disability of lower limbs between 40% and 50% will be considered. Such candidates need to produce disability certificated issued by duly constituted and authorized state medical board or central government institutions/hospitals. It doesnt talk about visual disabilities though. 

Coming to Disability parameters, AIIMS follows the MCI guidelines. The Supreme Court has recently ruled in the favour of a medical aspirant for admission into Medical College irrespective of his disability. However the % of disability allowed isnt mentioned. I would suggest you to reach out to the AIIMS help desk for the same.