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 and refractive surgery.
Gagan is a founding surgeon, board member and Chairman of the Medical Advisory Committee at Epping Surgery Centre.
He is a member of the Cataract Surgery and Implant unit at Macquarie University Hospital. He is also a member of the Australian, American and European Society of Cataract and Refractive Surgeons.
Dr Khannah has presented his research at local and international meetings as well as publications in international journals. He has also published a chapter in a book regarding cataract surgery techniques.
He is a Clinical Lecturer in the Department of Ophthalmology at the Sydney University and a Senior Lecturer at Macquarie University.