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Related to monochromasia: monochromatic


, achromatopsy (ă-krō'mă-top'sē-ă, a-krō'mă-top-sē), [MIM*216900, MIM*262300 & MIM*603096]
The complete form of achromatopsia, characterized by severe deficiency of color perception, associated with nystagmus, photophobia, reduced visual acuity, and "day blindness"; is of autosomal recessive inheritance. One form, Achromatopsia type 1, maps to chromosome 14. Achromatopsia type 2 is caused by mutation in the cone photoreceptor cGMP-gated cation channel, alpha-subunit 3 gene (CNGA3) on chromosome 2q. Achromatopsia type 3 is caused by mutation in the CNGB3 on 8q.
[G. a- priv. + chrōma, color, + opsis, vision]
Farlex Partner Medical Dictionary © Farlex 2012

complete colour blindness

The complete inability to discern colours; all visual stimuli are viewed as black, white or grey.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Complete absence of any perception of colour. Monochromasia is very rare. There is an absence or severe deficiency of cones in the RETINA and VISUAL ACUITY is poor. A person with this defect is called a monochromat.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005