Dr Khannah graduated from the University of Sydney and underwent specialist training at Sydney Eye Hospital and its affiliated teaching hospitals.
He has special interests in cataract & laser refractive surgery. Gagan is one of only 2 ophthalmic surgeons to perform and pioneer keyhole flapless LASIK surgery in Australia
He is a member of the intraocular implant unit for cataract surgery at Sydney Eye Hospital.
Dr Khannah is a member of the American, European and Australian Society of Cataract and Refractive Surgeons as well as the American Academy of Ophthalmologists. Gagan is a member of RANZCO and is on the board of the Australian Society of Ophthalmologists (ASO).
Dr Khannah has presented his research at local and international meetings as well as publications in international journals. He has also recently published a chapter in a book regarding cataract surgery techniques.
He is a Clinical Senior Lecturer in the Department of Ophthalmology at both Sydney University and Macquarie University and a former Staff Specialist at Sydney Eye Hospital