A form of energy necessary to see. Visible light is that part of the spectrum that produces sensation of sight in the human eye. The radiation wavelengths in this visible range are very small and are usually expressed in either millimicrons or nanometers. The values given for the limits of the visible- light wavelength range depend on the textbook you are reading, but are around 380-760 nanometers or 400-750 nanometers. The rays that cause us to see violet have the smaller, shorter wavelength, around 380 nanometers or millimicrons. Each color of the spectrum – blue, green, yellow and orange – have a range of wavelengths. Red has the highest range, at around 660-750 nanometers.

Low Vision

Term usually used to indicate vision of less than 20/20.

Low Vision Aids

Low-vision aids are devices designed to improve visual performance and can improve academic and social situations (among others).


The property of some optical lenses or systems of projecting a real inverted image of an object that is of a larger area than the object itself.

Major Reference Point

The point on a lens at which the specified distance prescription requirements shall apply (commonly but imprecisely referred to as the optical center).


The end user of products and services; the patient.

Mirror Coating

A thin deposit of appropriate material to the front surface of a lens, causing a portion of the light striking the lens to reflect directly from the front surface.

Mono Vision

A vision correction method where one eye is corrected for distance vision and the other is corrected for near vision.


Refers to only one eye or one side of a prism binocular.

Multifocal Lens

See Lens, Multifocal.


Nearsighted (difficulty seeing at distances).

Near Point

The closest point at which accommodation can be momentarily maintained; also called punctum proximum (PP).


A condition that usually starts in childhood and stabilizes in the late teens or early twenties. Because the eye’s focusing powers are too strong for the size of the eye, near objects are seen more clearly and those far away appear blurry. Light is focused in front of the retina (see Myopia).


The group of all eye care professionals who have contracted with the Claims Supervisor to provide Covered Service to Enrollees.


A device that excludes light from one or both eyes.


  1. An eyepiece.
  2. Pertaining to the eye.

Oculus Dexter (OD)

A term used by practitioners to refer to the right eye.

Oculus Sinister (OS)

A term used by practitioners to refer to the left eye.

Oculus Uterque (OU)

A term used by practitioners to refer to both eyes.

OLA (Optical Laboratories Association)

A trade organization for wholesale laboratories.