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.

glare

(glār) discomfort in the eye and depression of central vision produced when a bright light enters the field of vision, particularly when the eye is adapted to dark. It is direct g. when the image of the light falls on the fovea and indirect g. when it falls outside the fovea.

glare

a strong, dazzling light that may cause discomfort to the eye. Visual problems that result from glare often involve inadequate lighting conditions; they particularly affect individuals with cataracts or other disease conditions. The condition is relieved somewhat by using incandescent rather than fluorescent lighting, wearing a visor, wearing special antiglare lenses, and using a matte-black cardboard typoscope for reading words on a glaring white paper.

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.
References in classic literature ?
My gorge rose at the long, low billows-sleek as black satin - lifting and dipping in this ghastly glare.
Long lines of dull brick houses were only relieved by the coarse glare and tawdry brilliancy of public houses at the corner.
The man was hurrying to the door, when suddenly there came towards them on the wind, the loud and rapid tolling of an alarm-bell, and then a bright and vivid glare streamed up, which illumined, not only the whole chamber, but all the country.
The glare grew brighter, the roar of voices deeper; the crash of heavy bodies falling, shook the air; bright streams of sparks rose up into the sky; but louder than them all-- rising faster far, to Heaven--a million times more fierce and furious--pouring forth dreadful secrets after its long silence-- speaking the language of the dead--the Bell--the Bell!
The glare of the flames had sunk into a fitful, flashing light; and the gentle stars, invisible till now, looked down upon the blackening heap.
Mr Sampson became thoughtfully red, and felt called upon to encircle Miss Lavinia's waist with his arm; but, encountering a large pin in the young lady's belt, scarified a finger, uttered a sharp exclamation, and attracted the lightning of Mrs Wilfer's glare.
And stainless steel, which encases nearly the entire exterior, is so shiny, it causes eye-searing glares into the nearby business and homes.
Fast Open GL-based generators for lens flares, glints, glares