Ophthalmology is the study of medical conditions relating to the eye. An ophthalmologist is a specialist in ophthalmology. Most common diseases of eye includes: Cataract Glaucoma Macular degeneration Diabetic retinopathy Dry eyes Strabismus (misalignment/deviation of eyes) Proptosis (bulged eyes) Excessive tearing (tear duct obstruction) Uveitis Eye tumors.