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Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet (UV) rays from either natural (e.g. intense direct or reflected sunlight) or artificial (e.g. the electric arc during welding) sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva.
Flash blindness is caused by bleaching (oversaturation) of the retinal pigment. [ 2] As the pigment returns to normal, so too does sight. In daylight the eye's pupil constricts, thus reducing the amount of light entering after a flash. At night, the dark-adapted pupil is wide open, so flash blindness has a greater effect and lasts longer.
Uncommon (understudied) Visual snow syndrome ( VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or colored dots across the whole visual field. [ 7][ 4] Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and ...
While the macula is preserved there is some loss of pigmentation around it. Retinitis pigmentosa ( RP) is a genetic disorder of the eyes that causes loss of vision. [ 1] Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visual field). [ 1] As peripheral vision worsens, people may experience ...
Abundant visible light to the eyes gives health benefits through its association with the timing of melatonin synthesis, maintenance of normal and robust circadian rhythms, and reduced risk of seasonal affective disorder. [10] On the negative side, UV is a mutagen and carcinogen for skin.
Computer vision syndrome. Computer vision syndrome ( CVS) is a condition resulting from focusing the eyes on a computer or other display device for protracted, uninterrupted periods of time and the eye's muscles being unable to recover from the constant tension required to maintain focus on a close object.
Blurred vision. Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details. Temporary blurred vision may involve dry eyes, eye infections, alcohol poisoning, hypoglycemia, or low blood pressure. Other medical conditions may include refractive errors such as myopia, high ...
Pretty much everywhere in the U.S., the hottest part of the day is between 10 a.m. and 6 p.m. The body will gain heat from both the air temperature and solar radiation. The ground also heats up ...