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Glossary of Terms

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20/20—Sharp vision at 20 feet. One focuses and sees at 20 feet what others see at 20 feet.

20/30—One focuses and sees at 20 feet what others see at 30 feet.

20/10—One focuses and sees at 20 feet what others see at 10 feet.

Abbe Value—Named after Dr. Abbe, a value given to a lens that represents the amount of distortion (chromatic aberration). Higher Abbe Value numbers are better.

Anti-Reflective (AR)—Treatments applied to lenses that allow more light to pass through, reduce glare and reflections and are more scratch resistant.

ANSI 787.1—American National Standards Institute who oversees safety eyeglass regulations.

Aspheric—Lens designs that offer superior peripheral vision due to curvature changes.

Astigmatism—An irregular shaped (non sphere) cornea that results in poor vision.

Axis—The degree on which the astigmatic lens is placed. This ranges from 1-180.

Base Curve (BC)—The curve of the outside of the lens.

Bifocal—Lens designs that offer distance vision on the top portion and near vision on the bottom portion.

Bridge—The area on the eyewear frame that rests on the nose.

Blue Blocker—Lens tints/treatments that block out scattering and distracting blue light from the sun.

Cataracts—A clouding of the inner lens of the eye.

Clip-On—A small sunglass without temples that hooks on or has a magnet to attach to the front of frames.

Color Coated—Color that is applied to the lens surface.

Contrast—The clarity between an object and the space surrounding it. Patients with contrast sensitivity have a difficult time seeing at night and in low light areas.

Cornea—Tissue that surrounds the iris, pupil and anterior chamber of the eye.

CR39®—A trade name for plastic lenses. Columbia Resin created this lens material decades ago.

Cylinder—A curve correction in prescription lenses for patients with astigmatism.

Diopter–Number value of the strength of the lens.

DriveWear—A Transitions® lens by Younger Optics that will darken behind the windshield of a car. This lens is activated by visible light, not just UVR.

EN1836:2005—A standard for health and safety applied by European Union Countries to check that sunglasses conform to the health and safety requirements laid down in The European Directive 89/686/EEC.

Eye Size—The size of the lens in the frame measured in mm. Opticians refer to this as the A measurement.

Frame Measurements—The size of the lens, bridge and temples measured in mm. These can be found on the backside of the frame front and/or on the temples.

GLOSSARY OF TERMS

G 15—A lens color of dark green/gray. G15 lenses can be plastic, high index or glass.

Glass—A lens material that can also be high index. Glass lenses are heavier and have superior optical clarity.

Grilimid/Nylon—Frame material that is strong, lightweight, resilient, chemical and UVR resistant and perfect for extreme hot/cold environments.

High Index—Lenses in glass or plastic that are thinner, lighter and less bulbous. High index numbers are 1.60, 1.67, 1.70, 1.71, 1.74, 1.80 and 1.90. Generally speaking, the higher the number the thinner and lighter the lens.

Hyperopia—An eye that is farsighted. Patients who can not see clearly up close are Hyperoptic.

Infrared Radiation (IR)—Radiation from the sun that causes sunburn. Sunglass lenses must block out IR.

Lenses—Prescription or non-prescription devices set in frames.

Macular Degeneration—A disease of the eye that affects the central part of the retina located in the back of the eye. This degenerative disease can lead to blindness. Early detection is key when treating the eye.

Mid Index—Lenses in glass or plastic that are thinner, lighter and less bulbous. Mid index numbers are 1.54, 1.55, 1.56 and1.59.

Millimeter (mm)—One tenth of centimeter or one hundredth of a meter.

Mirrored Coating —A lens treatment placed on the front that reduces the amount of light and glare passing through.

Myopia—An eye that is nearsighted. Patients who can not see clearly at a distance are Myoptic.

Nose Pad—Small pads placed on the back side of the frame front that rest on the bridge of the nose.

Ocular—A word that represents the eye.

OD—Abbreviation for the right eye. Translated from Latin to English it means ocular dexter.

OS—Abbreviation for the left eye. Translated from Latin to English it means ocular sinister.

Photochromic—Properties of a lens that darkens outdoors and lightens indoors. Photochromic lenses are available in glass and plastic Transitions®.

Polarized—Sun lenses that contain a filter that blocks out excess light, harmful UVR and glare from the sun.

Polycarbonate—A lens material that is thinner, lighter weight, UVR absorbent and more impact resistant.

Presbyopia—An eye that can not focus up close. Mature patients who experience this are Presbyoptic.

Prism—Prisms bend light when it enters the lens. A lens with prescribed prism brings the light to the eye.

Progressive Addition Lens (PAL)—Multifocal lenses that do not have lines. PALs offer distance, intermediate and close up vision more naturally for the wearer.

Pupillary Distance (PD)—This distance between the right and left pupil measured in mm.

GLOSSARY OF TERMS

Round Seg—A segmented bifocal that is round instead of flat across the top.

Rx—Abbreviation for prescription. Frames that can be used for prescriptions are known as Rxable.

Scratch Resistant Coating (SRC)—Lens treatments applied to the lens surface that do not scratch as easily as uncoated lenses.

Sphere—An eye whose cornea does not have astigmatism.

Temple—The earpieces on the frame that fit over the ear. Temples are generally measured in mm.

Tints—Dyes or treatments that add color to the plastic and high index lenses.

Tensil Strength—The ability to be stretched without cracking.

Transitions® Lenses —Proprietary photochromic lenses in brown and gray.

Trifocal—Segmented lens designs that offer distance vision on the top portion, intermediate vision in the middle portion and near vision in the bottom portion.

TrivexT—A proprietary lens material that is mid index, light weight, thinner, posses superior optical clarity and has a higher tensil strength.

Ultra Violet Radiation (UVR) – Harmful radiation from the sun that causes cancer. Sunglass lenses must block out 100% UVR.

UV400 Filter – A lens treatment that blocks out harmful UVR up to 400 nanometers (nn).

Visible Light - Light from the sun that allow us to see. Visible light in the light spectrum is not harmful to the eye, although excessive exposure can affect night vision. Wearing sunglasses prevents this.

Wrap Frame – A frame with lenses that curves or wraps around the face. Rx lenses for wrap frames are known as high base curve lenses.