Oculus Uterque (OU)

A term used by practitioners to refer to both eyes.

OLA (Optical Laboratories Association)

A trade organization for wholesale laboratories.

OMA (Optical Manufacturers Association)

A trade organization for the manufacturers of ophthalmic frames and lenses.


With reference to the eye and its functions.


A medical doctor who has completed a residency program in ophthalmology and specializes in vision care that is related to medical conditions, such as treating diseases of the eye and performing ocular surgery. Title is M.D.


An instrument used to examine internal health of the eye.


A test for internal health of the eye.


Pertaining to light or the sense of sight.

Optic Nerve

The nerve that carries impulses from the eye to the brain.

Optical Axis

The line connecting the centers of curvature of a lens or system of lenses. The cardinal points lie on this line or its extensions. This is also referred to as the anterior-posterior axis of the eye.

Optical Center

A point on the lens axis midway between the nodal points.


A fabricator and dispenser of eyeglasses. Some opticians also fit contact lenses. An optician is skilled in the application of the science of optics, including optical lens and/or instrument designing or manufacturing.


A doctor of optometry, who provides all ophthalmic services except surgery. In most states, they are licensed to treat ocular diseases. Title is O.D.


A larger-than-standard lens required to fabricate eyeglasses.


An alternative term used to refer to the plan member or end user.

Peripheral Vision

Side vision. That which an eye can see to the side while looking straight ahead.


Lenses that turn brown when exposed to the sun.


Glass lenses that turn grey when exposed to the sun.

Photorefractive Keratectomy (PRK)

Refractive surgery to eliminate myopia by flattening the central portion of the cornea with a laser.

Photosensitive Lenses

Lenses that darken when exposed to the sun’s ultraviolet rays.