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Achromatopsia (ACHM) is a medical syndrome that exhibits symptoms relating to at least five conditions. The term may refer to acquired conditions such as cerebral achromatopsia, also known as color agnosia, but it typically refers to an autosomal recessive congenital color vision condition, the inability to perceive color and to achieve satisfactory visual acuity at high light levels (typically exterior daylight). The syndrome is also present in an incomplete form which is more properly defined as dyschromatopsia. It is estimated to affect 1 in 40,000 live births worldwide.〔() AAPOS-American Association for Pediatric Ophthalmology and Strabismus (USA, 2015)〕 There is some discussion as to whether achromats can see color or not. As illustrated in ''The Island of the Colorblind'' by Oliver Sacks, some achromats cannot see color, only black, white, and shades of grey. With five different genes currently known to cause similar symptoms, it may be that some do see marginal levels of color differentiation due to different gene characteristics. With such small sample sizes and low response rates, it is difficult to accurately diagnose the 'typical achromatic conditions'. If the light level during testing is optimized for them, they may achieve corrected visual acuity of 20/100 to 20/150 at lower light levels, regardless of the absence of color. One common trait is hemeralopia or blindness in full sun. In patients with achromatopsia, the cone system and fibres carrying color information remain intact. This indicates that the mechanism used to construct colors is defective. ==Terminology== Color blindness can be classified as: * Acquired achromatopsia (Cerebral achromatopsia) *Congenital/inherited achromatopsia * *Complete typical achromatopsia * *Incomplete atypical achromatopsia or incomplete atypical dyschromatopsia Related terms: *Achromatopsia–The complete lack of the perception of color in a subject, seeing only in black, white, and shades of grey. *Amblyopia–Defined conceptually by Duke-Elder (1973) as a monocular acuity deficit which is not due to refractive error or any organic abnormality. A neural condition. Poor spatial performance of the precision optical servomechanism of the eyes at nominal illumination levels without any morphological cause. One form of lazy eye. *Hemeralopia–Reduced visual capacity in bright light. Colloquially, day-blindness. *Nystagmus–This term is used variously to describe both normal and pathological conditions related to the oculomotor system. In the current context, it is a pathological condition involving an uncontrolled oscillatory movement of the eyes during which the amplitude of oscillation is quite noticeable and the frequency of the oscillation tends to be quite low. *Photophobia–The avoidance of bright light by those suffering from hemeralopia. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「achromatopsia」の詳細全文を読む スポンサード リンク
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