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

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 periodicals archive ?
* Indirect, layered lighting creates visual interest for sighted users without being glary.
You challenged readers to try for Mimas, Saturn's tiny satellite just outside the rings, because the rings are nearly edge on this year and much less glary than usual (April issue, page 54).
I must admit that the color and cutoff are a great improvement, albeit a bit more glary. Everything looks brighter due to the Purkinje shift into mesopic vision.
The annual Geminid meteor shower should peak on the night of December 13-14, when, unfortunately, the Moon will be just a day past full and at its glary worst late at night.
The glary sources and exposed fixtures distracted visitors from the objects on display, including books, artifacts and art.
They're about magnitude 10, 10 1/2, and 10 1/2, respectively, and become increasingly hard to see nearer to Saturn's glary disk.
The lighting at its Madison, WI, office was glary and outdated, but the company couldn't afford a complete renovation, so retrofit specialist Energy Performance Lighting devised a solution that would provide new lighting using the existing fixtures.
To enliven the streetscape, SWA looked for a pedestrian-level luminaire that would "create points of visible light [along the street], light people's faces without being glary or harsh and comply with the dark sky legislation," says Slaney.
They're about magnitude 10, 101/2, and 101/2, respectively, and become increasingly difficult to see as they get nearer Saturn's glary disk.
For most people, the term is synonymous with the dimly lighted corridors, unshielded, glary sources, and unsightly fl uorescent luminaires that plague commercial buildings around the nation.
Find a spot with an open sky view and no glary lights.