health-care profession concerned with examining the eyes (eye disease) for defects of vision and diagnosing and treating such conditions. Optometrists prescribe and supply eyeglasses, contact lenses, and other optical aids that correct the focusing of the eyes. They also examine the eyes to detect such disorders as glaucoma and cataracts. In addition, optometrists counsel people on the correct use and care of the eyes, supervise exercise and training programs that are designed to treat problems of vision, and help rehabilitate patients who have low or severely restricted vision. Unlike the ophthalmologist (ophthalmology), who is a physician with a specialization in the diagnosis and treatment of eye diseases (and who may also test vision and prescribe corrective lenses), the optometrist generally is not trained to perform surgery. In some areas, however, optometrists are licensed to use topical therapeutic drugs and to treat glaucoma and other eye diseases with systemic drugs.

Requirements for the practice of optometry vary. In the United States professional optometrists must complete a four-year course of study in addition to two to four years of undergraduate work and must be licensed by the state in which they practice. Schools of optometry are accredited nationally by the Council on Optometric Education and grant the Doctor of Optometry (O.D.) degree.

The optician, another optical specialist, makes, fits, and sells optical devices, particularly the corrective lenses prescribed by optometrists and ophthalmologists.