glare


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glare

(glār),
A sensation caused by brightness within the visual field that is sufficiently greater than the luminance to which the eyes are adapted; results in annoyance, discomfort, and decreased visual performance.
Farlex Partner Medical Dictionary © Farlex 2012

glare

A visual condition in which the observer feels either discomfort and/or exhibits a lower performance in visual tests (e.g. visual acuity or contrast sensitivity). This is produced by a relatively bright source of light (called the glare source) within the visual field. A given bright light may or may not produce glare depending upon the location and intensity of the light source, the background luminance, the state of adaptation of the eye or the clarity of the media of the eye.
direct glare Glare produced by a source of light situated in the same or nearly the same direction as the object of fixation.
disability glare Glare which reduces visual performance without necessarily causing discomfort.
discomfort glare Glare which produces discomfort without necessarily interfering with visual performance.
eccentric glare See indirect glare.
indirect glare Glare produced by an intense light source situated in a direction other than that of the object of fixation. Syn. eccentric glare.
glare source See glare.
glare tester An instrument for measuring the effect of glare on visual performance. There exist several (e.g. Brightness Acuity Tester (BAT), Miller-Nadler Glare Tester, Optec 1500 Glare Tester). Glare testing is valuable in patients with corneal and lenticular opacities before and after surgery and in elderly patients in whom adaptation to glare is usually more difficult. The Miller-Nadler Glare Tester consists of a glare source surrounding a Landolt C. The instrument contains 19 black Landolt C, all of the same size, 6/120 (or 20/400). Each Landolt C is presented in one of four orientations and from the highest to the lowest contrast at which the subject can no longer judge in which direction the letter appears. The contrast threshold is expressed in percentage disability glare.The
Brightness Acuity Tester (BAT) is a standardized glare source of light. It is presented in a hemisphere held over one eye. The light source can subtend a visual angle of 8 to 70 degrees at a vertex distance of 12 mm. The patient is asked to read a visual acuity chart through a small aperture in the hemisphere. The chart can be a low-contrast or high-contrast log MAR visual acuity chart or, for example, the Pelli-Robson contrast sensitivity chart.
veiling glare Glare caused by scattered light and producing a loss of contrast.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
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To reduce glare and relieve your eyes, add an anti-glare screen or hood to your monitor and, if you wear glasses, ask for an anti-reflective coating on your lenses.
The GLARE RECOIL represents the culmination of a decade of technological development, and also features the latest advancements in automatic power-control.
Luminance (new term for brightness) of the glare source
use a task light to illuminate paper documents, be sure to: select a low glare asymmetric lens, an adjustable position task light and place it in a convenient position to light coloured documents without causing reflected glare in the computer screen and position the task light to the side of the computer screen so that the light shines on paper documents rather than the monitor screen.
THE visibility really is impressive - as promised, there's no noticeable glare and colours do appear very clear and crisp through these shades.
A study sponsored by DSM and Kemin demonstrated how FloraGLO lutein and OPTISHARP zeaxanthin supplementation could improve the ability to see under glare conditions.