Vision Glossary

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The failure of a refracting surface or lens to bring all rays from an object point toward a desired image point. This can result in image blur. Aberration also results in curvature in the image of a straight line. It may be inherent in the lens design or may result from an error in processing.

A stretching or relaxing of the eye muscles, which causes a change in focal length of the crystalline lens, thereby producing clear images on the retina of objects that are relatively near the eye. Without the ability to accommodate, the image of the object would blur.

Add power or addition
1) The difference in front vertex power between the reading or intermediate portion of a multifocal lens and its distance portion.
2) Another term for the bifocal reading segment. In this case, the addition is a simple plus lens placed on top of a major distance lens.

Share or portion allotted or granted.

A condition in which the refractive power of one eye differs from that of the other eye.

Antireflective coating (A/R)
Lens coating that increases the transmittance of lenses by reducing surface reflections.

Absence or loss of the eye’s natural crystalline lens, as after cataract removal.

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Benefit Period
Benefit term from effective date to renewal date.

Bifocal Lens
A lens having one section that corrects for distant vision and another section that corrects for near vision. Addition to lens for reading; a simple plus lens placed on top of a distance lens to provide additional power for viewing items approximately 16 inches from eyes.

The basic lens substrate to which segments of different refractive power may be added to produce a multifocal lens.

Blank, molded
A blank that is unfinished on both sides when it arrives from the factory. It is used to grind lenses for non-standard prescriptions or prescriptions that are particularly strong.

Blank, semi-finished
Lens that has been ground and polished on only one side.

The supportive structural member connecting the two eyes of an ophthalmic frame front.

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Opacity of the lens or capsule of the eye, causing impairment of vision or blindness.

The portion of the cost that is paid by the member.

That portion of the eye through which light rays first enter and are bent or refracted.

Corneal Reflection
Method of measuring the distance from the pupil, using light reflected from the cornea to the center of the nose.

Crystalline Lens
That portion of the eye which further refracts the light and focuses it on the retina.

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Diabetic Retinopathy
A disorder of the blood vessels of the retina occurring as a complication of poorly controlled diabetes mellitus and often leading to blindness.

Diopter, prism
A unit of measurement used to express the angle of deviation of a ray of light by a prism or lens. In these units, prism power is measured in centimeters as the displacement of a light ray perpendicular to its line of incidence at a distance of one meter.

Distance, interpupillary
The linear distance between the fixation axes of the wearer’s two eyes. It is commonly referred to as the distance between the centers of the pupillary openings with the eyes focused on a distant object.

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Effective Date
Date on which the vision plan benefits are available to the member.
Enrollment Package: Provided to the employee or member to outline benefits and features of Advantica Vision plan.

Eye, Emmetropic
Another name for the normal eye, one that does not need corrective lenses.

Eye, Hyperopic
Farsighted eye, cannot focus on objects that are close up. This eye may be thought of as optically shorter than it should be.

Eye, Myopic
Nearsighted eye, unable to focus well on items that are in the distance.
Eyeglasses: A term commonly used to describe an ophthalmic frame with lenses inserted.

The component of an ophthalmic frame front which encircles one lens. Also called an eye.

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Process during which a lens is smoothed after generating.

Finished Lens
A lens that contains the lens power and other optical characteristics.

Frame (ophthalmic or spectacle)
A device for holding ophthalmic lenses in the proper position on the head in front of the eyes. A frame typically consists of a front that holds the lenses, and a pair of temples (earpieces) that secure the unit to the head.

Frame, combination
A frame whose front consists of a metal chassis with attached trim parts (sometimes known as top rims). These trim parts are typically plastic, aluminum or other metal, and are attached to the top portion of the chassis. These top rims may serve functional or cosmetic purposes, or both.

Frame, dress ophthalmic
A frame for prescription or corrective lenses, intended for ordinary use in correcting or improving vision. Such a frame is not intended for occupational or safety use.

Frame, rimless
A type of frame that provides no, or only partial, peripheral support for the lenses.

Frame, zyl
Frame made from cellulose acetate.

A component of an ophthalmic frame, typically consisting of a bridge and eyewires.

How often the benefits are available to the member.

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Groove, eyewire
The recessed area of an eyewire in which the lens edge is seated, also called the lens groove.

Group Number
Number that is assigned to an employer group to identify it, used by providers to help find the eligibility information.

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Part of the hardware of the frame. The hinges attach to both the temple and front of the frame.

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Index of Refraction

A measure of the ability of a lens material to refract a ray of light of a given wavelength.

That area in a trifocal lens or blank which has been designed to correct vision at ranges intermediate to distant and near objects.

Independent Provider
Single site provider not associated with large chain, open standard hours.

In-Network Provider
Provider who is contracted to provide services for Advantica members.

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A degenerative disease of the cornea that causes it to gradually thin and bulge into a cone-like shape.

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Lens size
The horizontal box dimension (A-dimension) of a finished lens. Also called eye size.

Lens, bifocal
A lens designed to provide correction for two viewing ranges.

Lens, crystalline
That portion of the eye which further refracts the light and focuses it on the retina.

Lens, cylinder
A special case of the sphero-cylinder lens in which one of the principal meridians has zero refractive power.

Lens, edged
A lens whose periphery has been ground (flat, beveled or grooved) to a specific size and shape.

Lens, full field
Lens in which the zone of the prescription optics extends to the edge of the lens.

Lens, high index
Lenses with a refractive index greater than 1.57.

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

Lens, minus
A lens having negative dioptric power. It is thinner at the center than at the edge.

Lens, multifocal
A lens designed for two or more viewing ranges; include bifocal, trifocal lenses, and PAL lenses.

Lens, myo-disk
Lens having a full-field curved or plano front surface with a high minus bowl-shaped surface on the ocular side surrounded by a plano surface called a carrier.

Lens, photochromic
A lens that changes color when ultraviolet radiation from the sun stricks them.

Lens, plano
A lens which has zero refractive power.

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

Lens, progressive power
A lens that is designed to provide correction for more than one viewing range in which the power changes continuously rather than discretely.

Lens, semi-finished
A lens that has only one surface finished.

Lens, single vision
Lens used to correct either distance or near vision, designed to provide correction for a single viewing distance.

Lens, spherical
A lens that has the same refractive power in all meridians. Such a lens may have rotationally symmetrical aspheric (reflective) surfaces.

Lens, surfacing
Grinding of finished optical lenses to meet prescribed optical characteristics and lens power.

Lens, toric
A lens which has two distinct curvatures, at right angles (90 degrees) to each other. See lens, sphero-cylinder.

Lens, uncut
A lens with finished optical surfaces on both sides but not edged for mounting in a frame.

Shaped like a biconvex lens.

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Macular Degeneration
Degeneration of the central portion of the retina, resulting in a loss of sharp vision.

Medically Necessary Contact Lens
Limited to specific eye disorders and requires pre authorization by Advantica.

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A Medical Doctor who specializes in Ophthalmology, which is the branch of medicine which deals with the diseases and surgery of the visual pathways, including the eye, brain, and areas surrounding the eye. An Ophthalmologist is specialized in diagnosing and prescribing treatment for defects, injuries, and diseases of the eye. Ophthalmologists are trained to provide the full spectrum of eye care, from prescribing eyeglasses and contact lenses to performing complex and delicate eye surgery. They may also be involved in eye research.

Optical center
The thinnest point of minus lenses and the thickest point of plus lenses. The point at which the refractive power is measured.

One that makes lenses and eyeglasses.

A person who is professionally trained and licensed to examine the eyes for visual defects, diagnose problems or impairments, and prescribe corrective lenses or provide other types of treatment.

Order form, prescription
Order form that originates with the customer. It gives the name of the doctor, the name of the patient, and a description of the desired product.

Latin abbreviation meaning left eye.

Latin abbreviation meaning both eyes.

Out-of-Network Provider
Provider who is not contracted with Advantica to provide services.

Out-of-Network Re-imbursement Form
Form used to submit out of network re-imbursement request to Advantica.

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Abbreviation for progressive addition lens.

Abbreviation for interpupillary distance.

Power, cylinder
The difference (plus or minus) between the powers measured in the two principal meridians of a lens.

Power, refractive
The ability of a lens or an optical surface to produce a change in the convergence or divergence of a beam of light, usually expressed in diopters.

Power, sphere
In a spherical lens, the dioptric power of the lens. In a sphero-cylinder lens, the sphere power is located in the cylinder axis meridian.

Capable of changing color on exposure to radiant energy (as light).

Progressive Lens
A multifocal eyeglass lens that provides a continuous range of focal power between near and far distances.

Eye care professional who renders services for Advantica members.

Provider Network
All of the contracted providers with Advantica that comprise our national vision network.

Pupillary distance, binocular
The measurement between the patient’s pupils, expressed in millimeters. Also called IPD.

Pupillary distance, monocular
The measurement from the center of the nose to the pupil. Also called MPD.

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The bending of light rays caused by prisms and lenses.

Retail Provider
Chain or franchise usually many locations, usually open department store hours.

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A specified area of a multifocal lens having different power from the major portion. This also may refer to the actual piece of material added to the lens in the case of a fused or cemented multifocal lens. Also called the addition.

Select Discount Plan
Included with all Advantica Vision plans for continued value once benefits have been utilized.

Single Vision Lens
Lenses that have the same focal power throughout (top to bottom) and can be used to correct nearsightedness, farsightedness, astigmatism, or a combination of these disorders.

An ophthalmic device consisting of two ophthalmic lenses and a supporting frame to position and retain the lenses in proper optical alignment with the eyes. Also called eyewear.

Surface, aspheric
A nonspherical surface curvature commonly used to improve optical performance, particularly for high refractive powers. Such curvatures are often derived from the oblique intersection of a plane and a conical surface, and are referred to as “conoids” or “conic” sections.

Surface, plano
A flat surface having zero surface power, or an infinite radius of curvature.

Surface, spheric
A curved surface having the same radius of curvature in all meridians.

Surface, toric
A surface in the form of a torus having different powers in two principal meridians. The shape may be visualized as that of a section cut from a doughnut or from a football-shaped surface.

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Temple screws
Tiny screws which connect the front and temple halves of the hinges.

A style of temple that has a slight bend which allows the frame to fit easily over the ear, and to hug the head lightly.

Surface form of lens having two distinct curvatures at right angles to each other.

Makers of photochromic lenses.

Trifocal Lens
A lens having one section that corrects for distant vision, a second section that corrects for intermediate vision and a third that corrects for near vision.

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A local ripple-like irregularity in a lens surface.

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