GLOSSARY

ACCOMMODATION
The adjustment in the lens of the eye, to permit continuous and accurate focusing on objects at different distances.
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	• Corporate Background • Glossary of Technical Terms

ANTI-REFLECTIVE LENSES (AR)
Anti-reflective lenses eliminate the glare and discomfort caused by working long hours at the computer. They are particularly helpful in working environments where there are numerous sources of light, such as offices with outside windows, desk lamps and overhead fluorescent lighting. AR is highly recommended for all computer eyewear.
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COMPUTER VISION SYNDROME (CVS)
The complex of eye and vision problems related to near work experienced during computer use. Symptoms include eye fatigue, double/blurred vision, burning/irritated eyes, neck, back and shoulder pain.
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CONVERGENCE
The coordination, or turning, of the eyes to aim at a nearby object. Convergence has to do with the eyes working together to focus on an image, but not whether or not they focus on the image. Convergence is tested using a fixation disparity test.
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ERGONOMICS
The science of adapting the office environment to work better with the human form, thus eliminating points of stress that may manifest themselves in injuries to the body, such as neck and shoulder musculoskeletal injuries (MSDs).
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FIXATION DISPARITY TEST
A near-vision convergence test to measure a patient's ability to aim both eyes directly at the same point. Fixation disparity can be corrected optically.
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GAUSSIAN
A mathematical equation describing any physical phenomena such as waveforms, which when measured or plotted, produce a bell-shaped curve (versus a sharp-edged or "square" wave).
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GAUSSIAN VISION TESTING
A means of examining the eyes that accounts for the smooth, bell shaped distribution of light which is characteristic of the pixels, or points of light, on a computer display.
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LAG OF ACCOMMODATION
The distance between where the eye should be focusing (at on a computer screen), and the "resting point of accommodation" (RPA), which is where the eye naturally focus when it has nothing to focus on. When looking at a computer, our focus "lags" from the plane of the screen toward the natural RPA, which is behind the screen, because the images on a computer screen are made up of "pixels" which are brighter at their centers than on their edges. Pixels don't provide the sharp definition the eye needs to focus accurately. (See resting point of accommodation)
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LENS COATINGS
Any of a number of surfaces placed upon a lens to filter the light coming through it. For example, a lens coating may toughen the surface of a plastic lens, diminish the amount of light, or correct the color of light passing through it. Option that may be prescribed by the doctor.
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NEAR VARIABLE FOCUS LENSES
The most advanced lens design on the market today. The lenses allows for the widest midrange viewing for computer work, reading at the bottom of the lens and some distance (10’-13” ft.) out the top for some distance. Highly recommended for most computer users.
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OPHTHALMOLOGIST
A physician and surgeon who specializes in the anatomy, function, pathology, and treatment of the diseases of the eye.
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OPTICIAN
A optics professional who is trained in the physics of how light changes as it passes through lens materials; someone who specializes in the design, grinding, or manufacturing of lenses, eyeglasses, or other optical instruments.
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OPTOMETRIST
A physician who specializes in examining, diagnosing, measuring and treating certain near vision defects through the use of corrective lenses. In 40 of the 50 states, optometrists may also treat eye diseases, which don't require surgery.
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PRESBYOPIA
The inability of the eye to focus sharply on nearby objects resulting from the hardening of the crystalline lens due to advancing age. Usually occurs after 40 years of age.
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PRIO VISION EXAM
An exam that uses a simulated computer screen, instead of ink-on-paper, to measure the lag of accommodation when viewing a computer screen. The exam allows the doctor to prescribe lenses that will bring the patient's natural resting point of accommodation to the same plane as the computer screen t hereby eliminating computer eyestrain.
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PIXELS
The small, bright points of light that make up the letters or pictures displayed on computer screens or other visual displays. These points of light are brighter at their centers than their edges, which make it difficult for the human eye to focus on them.
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RESTING POINT OF ACCOMMODATION (RPA)
The point in space that the human eye focuses when there isn't sufficient visual reference information to provide a detectable target. RPA varies from person to person.
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SNELLEN TEST
A common test (“Big E” card) of visual accommodation consisting of rows of letters, each row of decreasing size, printed with black ink on white paper. This test measures the patient's ability to resolve detail to the accepted 20/20 standard.
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VIEWING DISTANCE
The recommended distance between a computer screen and the eye. Usually 18 to 24 inches.
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