opto-

Also opti‑.

Vision; light.

Greek optos, seen.

Optometry is the occupation of measuring eyesight, prescribing corrective lenses, and detecting eye disease. The form appears in a few terms relating to the use of light in electronics, especially optoelectronics (or optronics), the branch of technology concerned with the inter-conversion of electronics and light; and optocoupler, a device containing light-emitting and light-sensitive components, used to couple isolated circuits.

Words in opti‑ come from Latin opticus or optica, which derive from the same Greek source. Examples are optic and optical, of or relating to the eye or vision; optics, the scientific study of sight and the behaviour of light; and optician, a person qualified to prescribe and dispense glasses and contact lenses, and to detect eye diseases.