An ophthalmologist is a doctor – an M.D. – with expertise in medical and surgical eye problems who performs operations on the eyes.
An optometrist is a doctor who assists patients with the health of the eyes and related vision. Optometrists are trained to prescribe and fit lenses to improve vision. They also diagnose and treat various eye diseases.
An optician is a specialized practitioner who designs, fits and dispenses lenses for the correction of a person's vision. Opticians determine the specifications of various ophthalmic solutions – from prescription, to eyeglass frames, to lens technology – that will give the necessary and best correction to a person's eyesight.