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Encyclopedia > Achromatopsia
Achromatopsia
Classifications and external resources
ICD-10 H53.5
ICD-9 368.54
OMIM 216900 262300
DiseasesDB 83
MeSH D003117

Achromatopsia is the inability to see color. Although the term may refer to acquired disorders such as color agnosia and cerebral achromatopsia, it typically refers to congenital color vision disorders (i.e. more frequently rod monochromacy and less frequently cone monochromacy). The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... // H00-H59 - Diseases of the eye and adnexa (H00-H06) Disorders of eyelid, lacrimal system and orbit (H00) Hordeolum and chalazion (H000) Hordeolum and other deep inflammation of eyelid (H001) Chalazion (H01) Other inflammation of eyelid (H010) Blepharitis (H011) Noninfectious dermatoses of eyelid (H02) Other disorders of eyelid (H020) Entropion... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The Diseases Database is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Color is an important part of the visual arts. ... Headline text COLOR AGNOSIA http://nanonline. ... There are very few or no other articles that link to this one. ... Achromatopsia is a medical condition (also called maskun or rod monochromatism) characterized by a low or nonexistent cone cell count or morphologically malformed cone cells; these are the light receptors responsible for color perception. ... ...

Contents

Classification

  • Acquired achromatopsia (Cerebral achromatopsia)
  • Congenital/inherited achromatopsia
  • Complete/typical achrompatopsia (Rod monochromacy)
  • Incomplete/atypical achromatopsia

Acquired achromatopsia (Cerebral achromatopsia)

Cerebral achromatopsia is a form of acquired color blindness that is caused by damage to the cerebral cortex of the brain, rather than abnormalities in the cells of the eye's retina. Color blindness in humans is the inability to perceive differences between some or all colors that other people can distinguish. ... Location of the cerebral cortex Slice of the cerebral cortex, ca. ... Human eye cross-sectional view. ...


Congenital / inherited achromatopsia

Complete / typical achromatopsia (Rod monochromacy)

Typical achromatopsia, also known as complete achromatopsia[1][2] or rod monochromatism[1], is associated with absent color vision, nystagmus, reduced visual acuity, and light aversion.[3]


Rod monochromacy, also known as total color blindness[4], achromatopsia[4], typical monochromacy[5], or complete achromatopsia[6], is a rare, nonprogressive inability to distinguish any colors as a result of absent or nonfunctioning retinal cones. It is associated with light sensitivity (photophobia), involuntary eye oscillations (nystagmus), and poor vision.[7] The word Rod may have one of the following meanings. ... Blindness is the condition of lacking visual perception due to physiological or psychological factors. ... Photophobia (also light sensitivity) is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. ... Nystagmus is rapid involuntary rhythmic eye movement, with the eyes moving quickly in one direction (quick phase), and then slowly in the other (slow phase). ...


Rod monochromatism is also known as achromatopsia[8], complete achromatopsia[1][9][3], and typical achromatopsia.[1][3]


Rod monochromacy is characterized by a low or nonexistent cone cell count or morphologically malformed cone cells; these are the light receptors responsible for color perception. Those with the condition have difficulty seeing in bright daylight because their rod cells (the receptors responsible for detecting brightness) are saturated. People with normal color vision do not perceive things in the same way as those with rod monochromacy, because they depend on color more than on luminosity to identify objects and patterns, whereas achromatopics depend almost entirely on luminosity to identify patterns. The closest that normal-sighted persons can come to experiencing rod monochromatic-type vision is in the dark, when the rod cells become the predominant receptors for vision due to their sensitivity to variations in brightness. Achromatopsia can vary in its severity from being mild enough that it is not diagnosed to causing near blindness. It is a relatively rare condition requiring two recessive genes (CNGA3 and CNGB3). In the United States, it affects approximately 1 in 33,000 people. The condition is generally stable over the course of one's life. Many achromats function normally with the aid of darkened lenses, while others use guide dogs, canes, and are considered legally blind. Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina of the eye which only function in relatively bright light. ... Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... Luminous intensity is a measure of the energy emitted by a light source in a particular direction. ... It has been suggested that this article or section be merged into Dominance relationship. ... A lens. ... A blind man is led by his guide dog in Brasília, Brazil. ... Blindness is the condition of lacking visual perception due to physiological or psychological factors. ...


Rod monochromacy is endemic on the atoll of Pingelap (where it is called maskun, literally "not see", by the locals) and was described by Oliver Sacks in The Island of the Colour-blind.[2] Sacks went there with Knut Nordby, a Norwegian man who had maskun, and the book narrates his experiences on the island. In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. ... World Class Surf of Pohnpeis Palikir Pass a. ... Oliver Sacks Oliver Wolf Sacks (born July 9, 1933, London) is a neurologist who has written popular books about his patients. ...


Incomplete / atypical achromatopsia

Atypical achromatopsia, also known as incomplete achromatopsia[1][10], is associated with normal visual acuity and absence of nystagmus.[10]


References

  1. ^ a b c d e Michaelides M, Hunt DM, Moore AT. "The cone dysfunction syndromes." Br J Ophthalmol. 2004 Feb;88(2):291-7. PMID 14736794.
  2. ^ "Typical achromatopsia". Drugs.com. Accessed October 5, 2006.
  3. ^ a b c "Complete achromatopsia". Drugs.com. Accessed October 4, 2006.
  4. ^ a b Deeb SS. "Molecular genetics of colour vision deficiencies." Clin Exp Optom. 2004 Jul;87(4-5):224-9. PMID 15312026.
  5. ^ Alpern M. "What is it that confines in a world without color?" Invest Ophthalmol. 1974 Sep;13(9):648-74. PMID 4605446.
  6. ^ Pokorny J, Smith VC, Pinckers AJ, Cozijnsen M. "Classification of complete and incomplete autosomal recessive achromatopsia." Graefes Arch Clin Exp Ophthalmol. 1982;219(3):121-30. PMID 6983472.
  7. ^ Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainsville, Florida: Triad Publishing Company, 1990.
  8. ^ Windsor RL, Windsor RK. "Understanding Achromatopsia." Accessed October 4, 2006. [1]
  9. ^ "Ben Simon GJ, Abraham FA, Melamed S. "Pingelapese achromatopsia: correlation between paradoxical pupillary response and clinical features." Br J Ophthalmol. 2004 Feb;88(2):223-5. PMID 14736779.
  10. ^ a b "Atypical achromatopsia". Drugs.com. Accessed October 5, 2006.

External links


  Results from FactBites:
 
Achromatopsia - Wikipedia, the free encyclopedia (277 words)
Achromatopsia is a medical condition (also called maskun or rod monochromatism) characterized by a low cone cell count or lack of function in cone cells; these are the light receptors responsible for color perception.
The closest that normal-sighted persons can come to experiencing maskun-type vision is in the dark, when the rod cells become the predominant receptors for vision due to their sensitivity to variations in brightness.
Achromatopsia can vary in its severity from being mild enough that it is not diagnosed to causing near blindness.
Achromatopsia and the underlying bioelectrochemistry (4982 words)
Achromatopsia (with an s) is a stationary congenital syndrome that is easily recognized in the clinic.
The principle interest, in the syndrome known as achromatopsia, is a failure in all of the signal paths shared by the chrominance channels, the luminance channel and the servomechanism associated with the analytical channel.
Achromatopsia (with an s) is a complex medical condition, labeled a syndrome, consisting of a number of commonly observed underlying individual conditions.
  More results at FactBites »


 

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