Disease or Syndrome
achromatopsia
[ ey-kroh-muh-top-see-uh ]
Etymology:
Greek a = not + chroma = color + opsis = vision
Definitions related to achromatopsia:
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Achromatopsia is characterized by reduced visual acuity, pendular nystagmus, increased sensitivity to light (photophobia), a small central scotoma, eccentric fixation, and reduced or complete loss of color discrimination. All individuals with achromatopsia (achromats) have impaired color discrimination along all three axes of color vision corresponding to the three cone classes: the protan or long-wavelength-sensitive cone axis (red), the deutan or middle-wavelength-sensitive cone axis (green), and the tritan or short-wavelength-sensitive cone axis (blue). Most individuals have complete achromatopsia, with total lack of function of all three types of cones. Rarely, individuals have incomplete achromatopsia, in which one or more cone types may be partially functioning. The manifestations are similar to those of individuals with complete achromatopsia, but generally less severe. Hyperopia is common in achromatopsia. Nystagmus develops during the first few weeks after birth followed by increased sensitivity to bright light. Best visual acuity varies with severity of the disease; it is 20/200 or less in complete achromatopsia and may be as high as 20/80 in incomplete achromatopsia. Visual acuity is usually stable over time; both nystagmus and sensitivity to bright light may improve slightly. Although the fundus is usually normal, macular changes (which may show early signs of progression) and vessel narrowing may be present in some affected individuals. Defects in the...GeneReviewsUniversity of Washington, 2021
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An autosomal recessive genetic disorder affecting the cone cells of the eye. It may be complete, in which the individual can only perceive black, white, or shades or gray, or incomplete, in which the individual has a residual amount of color vision.NCI ThesaurusU.S. National Cancer Institute, 2021
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Severely deficient color perception, typically with monochromacy and reduced visual acuity. The atypical form can include normal visual acuity with pseudomonochromacy.NLM Medical Subject HeadingsU.S. National Library of Medicine, 2021
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