Hope you are doing good.

To answer your question honestly, there is no concession for BSC nursing graduates in CDS exam.

If you want to join military there is a different provision for nursing graduates. CDSE does not recruit for medical branches aur medical related branches.

Regarding your eye surgery problem. It completely depends on the complexity of the surgery. if the surgery was Complex enough that it would create a problem in your eyesight in the coming years then the the Army doctors would not allow you to join during the medical checking.