These lenses have fewer reflection distractions for the wearer. They enhance colors, clarity, and the amount of light coming through a lens to the eye. Lenses without A/R lose between 8% and 18% of the light transmittance due to reflections and depending on the index of refraction of the lens material. Higher index lenses reflect more light, so A/R in highly recommended on any High index lens. Regardless, A/R helps the light transmittance of any lens. Today's Anti-reflective coatings are stronger and more resistant to wear and tear than coatings from just a few years ago. Also, different coatings perform at different levels, so choosing which one to use would be dependant on the patient needs.

Also known as cataract lenses. A high plus-power lens for optical correction of the absence of the crystalline lens, usually following cataract extraction. Less frequent these days due to cataract surgery improvements.

Lens which departs from a fixed radius of curvature (spherical) and hence is free from or has reduced spherical errors. Not noticeable to the naked eye, but it helps cut down the weight and thickness of lenses while enhancing optical performance.

Atoric lenses utilize aspheric design on both sides of the lens which produces the best acuity by reducing distortion due to astigmatism.

Vertical placement of prism so that the base of the prism is toward the bottom of a lens or at 270 degree on a 360 degree scale.

Horizontal placement of prism so that the base is toward the nose along the 180 degree line. For the right eye, at 0 degree and for the left eye, at 180 degree on a 360 degree scale.

Horizontal placement of prism so that the base is toward the side of the head along the 180 degree line. For the right eye, at 180 degree and for the left eye at 0 degree on a 360 degree scale.

A multifocal ophthalmic lens designed to provide correction for two distinct viewing ranges (distance and near). The upper part of the lens is in the top part of the lens, while the near portion is in the bottom part, or "segment." These segments are available in different widths (22, 25, 28, 35, 45, exec), although 28 wide segments are the most populous today.

Designed to maintain clear, uninterrupted continuous vision from reading distance to up to intermediate distance of about seven feet away. Good for computer users, musicians, artists and hobbyists. Most computer lenses are made in a similar design as progressive lenses.

Ophthalmic lens in which one of the principal meridians has zero refractive power.

A multifocal lens with a flat, edged segment both at the upper and lower extremities of the lens, helpful for overhead work.

Multifocal lens with a straight horizontal dividing line deliminating the upper edge of the segment.

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

A lens, usually of 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, which provides little or no refraction, but instead gives desirable dimensions to the lens for assembly.

A lens having minus dioptric power; thinner at the center than at the edge.

An ophthalmic lens designed to provide correction for two or more viewing ranges (i.e. bifocal, trifocal, etc...)

In correction of high myopia, a lenticular lens, having a concave, central area and a flat carrier area.

A piece of transparent and homogenous substance having two highly polished, opposing, refracting surfaces for use close to the eye to assist the functions of the eye.

Lenses that darken on exposure to light, and lighten with reduced exposure. Today's photochromic lenses get darker in a shorter amount of time, and lighten almost as quickly. They are available in almost all designs and materials. They also protect eyes from harmful UV light. It is important to note that most photochromic lenses depend on UV light to darken, and therefore do not replace driving sunglasses because UV light does not penetrate car windshields. Plano Lens

A lens having zero refractive power

A lens having positive dioptic power; thicker at the center than at the edge.

Polarized lenses are specifically designed to eliminate glare. Light reflecting from surfaces are polarized horizontally, and can be eliminated by using a vertically oriented polarized filter. It works by eliminating undesirable light, while allowing other light to pass through.

An ophthalmic lens which the power changes continuously rather that discretely in order to provide correction for more than one viewing range.

A multifocal ophthalmic lens having four finite focal distances, usually a typical trifocal with one additional segment at the top for above-eye-level viewing.

An ophthalmic lens with a flat or faceted edge for use in mountings without rims or eye wires.

A generic term for various ophthalmic lenses designed to protect the eye from injury.

Nothing is scratch proof, but today's scratch coatings hold up well to normal everyday wear.

An ophthalmic lens designed to provide correction for only one viewing distance.

A process of surfacing or molding an ophthalmic lens to reduce vertical prismatic effect in the reading portion of a lens without affecting the error-free point of the distance portion of the lens. Used to balance vertical prismatic effects induced by anisometropic correcting lenses. Also known as bicentric grinding.

A lens that has the same refractive power in all meridians. Such a lens may have rotationally symmetrical aspheric surfaces

A lens having different refractive powers in its two principal meridians. It is sometimes referred to as a toric lens or, incorrectly, as a cylinder lens.

An ophthalmic lens with both surfaces finished to specific back vertex power(s) supplied by a manufacturer. Such a lens has yet to be edged to a specific shape.

Sun Lenses
Sun Lenses are lenses that have a mirror coating and are usually very dark in appearance. These lenses help reduce light transmission and come in many colors such as yellow, blue, mirror etc.

A multifocal, ophthalmic lens designed to provide correction for three viewing distances. Standard trifocals have intermediate power of 50% of the near vision addition. (Actual amount should be specified by the manufacturer, ordinarily from 40% to 75% of the near vision add).

An ophthalmic lens that has been ground and polished on both sides to a specific prescription power and thickness, but not yet sized, edged to shape.