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Photophobia is a medical symptom of abnormal intolerance to visual perception of light. [1] As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, [2] though the term is sometimes additionally applied to abnormal or irrational fear of light, such as ...
Phosphene. An artist's representation of how some people may see phosphenes by retinal stimulation. A phosphene is the phenomenon of seeing light without light entering the eye. The word phosphene comes from the Greek words phos (light) and phainein (to show).
Blue light, a type of high-energy light, is part of the visible light spectrum. High-energy visible light (HEV light) is short-wave light in the violet/blue band from 400 to 450 nm in the visible spectrum, which has a number of purported negative biological effects, namely on circadian rhythm and retinal health (blue-light hazard), which can lead to age-related macular degeneration.
Eccentricity effect. The eccentricity effect is a visual phenomenon that affects visual search. As retinal eccentricity increases (i.e. the light of the image enters the eye at a larger angle and approaches peripheral vision), the observer is slower and less accurate to detect an item they are searching for. [ 1]
Amblyopia. Anisometropia is a condition in which a person's eyes have substantially differing refractive power. [ 1] Generally, a difference in power of one diopter (1D) is the threshold for diagnosis of the condition. [ 2][ 3] Patients may have up to 3D of anisometropia before the condition becomes clinically significant due to headache, eye ...
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflected by objects in the environment. This is different from visual acuity, which refers to how clearly a ...
Ocular dominance. Ocular dominance, sometimes called eye preference or eyedness, [ 1] is the tendency to prefer visual input from one eye to the other. [ 2] It is somewhat analogous to the laterality of right- or left- handedness; however, the side of the dominant eye and the dominant hand do not always match. [ 3]
Eye examination for visual acuity. Visual acuity is a measure of the spatial resolution of the visual processing system. VA, as it is sometimes referred to by optical professionals, is tested by requiring the person whose vision is being tested to identify so-called optotypes – stylized letters, Landolt rings, pediatric symbols, symbols for the illiterate, standardized Cyrillic letters in ...