Optometrist: A practitioner who provides primary eye and vision care, performs eye examinations to detect vision problems, and prescribes corrective lenses to correct those problems. Some optometrists also make and fit eyeglasses, but many leave that job to opticians. An optometrist is a doctor of optometry (OD), not an MD. When an optometrist detects eye disease, the patient may be referred instead to an ophthalmologist, a physician who specializes in evaluating and treating diseases of the eye.