A medical doctor who specializes in the diagnosis and medical or surgical treatment of eye diseases. To become an ophthalmologist one must first obtain a medical degree (M.D. or D.O. in North America) and then complete further specialty training. A medical degree typically takes 7 or 8 years university training and a specialist certification an extra 3 years in the USA or 4 years in Canada. Specialist MD's are usually divided into "medical" and "surgical" disciplines. Ophthalmology is technically a "surgical" discipline. Some ophthalmologists chose not to perform surgery and can be called "medical ophthalmologists". An ophthalmologist may also prescribe eyeglasses and contact lenses. Visit ophthalmology, optometry, and opticianry, to compare the three disciplines of eye care.