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Color blindness is any deviation of color vision from normal trichromatic color vision (often as defined by the standard observer) that produces a reduced gamut. Mechanisms for color blindness are related to the functionality of cone cells , and often to the expression of photopsins , the photopigments that 'catch' photons and thereby convert ...
The second most common PIP color vision standard is the HRR color test (developed by Hardy, Rand, and Rittler), which solves many of the criticisms of the Ishihara test. For example, it detects blue-yellow color blindness, is less susceptible to memorization and uses shapes, so it is accessible to the illiterate and young children. [2]
Achromatopsia, also known as rod monochromacy, is a medical syndrome that exhibits symptoms relating to five conditions, most notably monochromacy.Historically, the name referred to monochromacy in general, but now typically refers only to an autosomal recessive congenital color vision condition.
Color vision is categorized foremost according to the dimensionality of the color gamut, which is defined by the number of primaries required to represent the color vision. This is generally equal to the number of photopsins expressed: a correlation that holds for vertebrates but not invertebrates .
Dichromacy in humans is a form of color blindness (color vision deficiency). Normal human color vision is trichromatic, so dichromacy is achieved by losing functionality of one of the three cone cells. The classification of human dichromacy depends on which cone is missing: Protanopia is a severe form of red-green color blindness, in which the ...
Research has shown that scores below twelve indicate color vision deficiency, and twelve or more correct indicate normal color vision, with 97% sensitivity and 100% specificity. The sensitivity of the Ishihara test varies by the number of plates allowed to pass, which can vary by institutional policy.
Rod monochromacy (Achromatopsia), when all three of the cones are non-functional and therefore photopic vision (and therefore color vision) is disabled. Monochromacy of photopic vision is a symptom of both Cone Monochromacy and Rod Monochromacy, so these two conditions are typically referred to collectively as monochromacy. [1] [2]
Cerebral achromatopsia is a type of color blindness caused by damage to the cerebral cortex of the brain, rather than abnormalities in the cells of the eye's retina.It is often confused with congenital achromatopsia but the underlying physiological deficits of the disorders are completely distinct.