Lens, Plus

A lens that has positive refractive power. It is thicker at the center than at the edge.

Lens, Plano

A lens that has zero refractive power.

Lens, Plastic Photochromic

Plastic photochromic lenses are light-adaptive and darken when they are exposed to ultraviolet rays. The most common brand is called Transitions® adaptive lenses or generic versions called, photochromic or photosensitive lenses, these lenses provide the wearer protection from the harmful effects of the sun.

Lens, Pattern

A cam, or template, used in lens-edging equipment to generate the correct peripheral shape and geometric center location. Also called a lens former.

Lens, One-piece Multifocal

A multi-focal lens or a lens blank fabricated from a single piece of glass or plastic.

Lens, Multifocal

A lens designed for two or more viewing ranges for example, bifocal or trifocal lenses.

Lens, Lined Bifocal

A lens designed for two viewing ranges. The upper part of the lens is used for distance vision and the lower part of the lens is used for near vision.

Lens, Lenticular

A lens, usually of strong refractive power, in which the prescribed power is applied over only a limited central region of the lens, called the lenticular portion. The remainder of the lens, called the carrier, provides no refractive correction but gives dimension to the lens to allow for mounting in a spectacle frame.

Lens, HD Progressive

Commonly referred to as free-form lenses, this new optimized lens design offers the latest in progressive lens technology and is ideal for people with specific visual needs. This includes those who are new to progressives and needing them for the first time. Also suitable for those motivated to wear progressive lenses, but have had issues adapting to them in the past, as well as current progressive wearers interested in the latest technology.

Lens, Glass Photochromic

Lens that changes to a cosmetic sunglass in the direct sunlight.

Lens, Corrected Curve

A lens designed to reduce peripheral power errors for the conditions of intended use over a specified portion of the field of view.


A transparent medium bounded by two geometrically defined surfaces, one of which is curved that is, spherical, cylindrical, toroidal or aspheric.


Acronym: Laser in Situ Keratomileusis. Type of refractive surgery in which the cornea is reshaped to change its optical power.


A condition (cause unknown) in which the cornea gets progressively steeper (cone-shaped). Fitting with a hard contact lens may slow progression. Surgery may eventually be necessary.


Inflamed cornea.


An instrument used to measure the curvature of small areas of the cornea by reflected light.


Colored part of eye.


Within the eye.

Intermediate Examination

Describes a level of service pertaining to the evaluation of a new or existing condition complicated with a new diagnostic or management problem. This does not necessarily relate to the primary diagnosis. It includes history, general medical observation, external ocular and adnexal examination and other diagnostic procedures as indicated; it may include the use of mydriasis.

Intermediate-vision Lenses

That area in a trifocal lens or lens blank that has been designed to correct vision at intermediate to distant ranges.

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