Ophthalmologists are eye doctors that have received higher levels of training than both opticians and optometrists, and can also perform eye surgery when necessary.
Opticians design and fit eyeglasses, frames, and lenses that are prescribed by optometrists and ophthalmologists. They do not perform vision tests or write prescriptions for visual aids.
Optometrists fall between ophthalmologists and opticians. Optometrists can detect and treat eye abnormalities, prescribe lenses, and complete eye exams, but cannot perform eye surgery.