Knowra Monochromacy Monochromacy Monochromacy is a form of color vision deficiency in which vision depends on one functioning cone class or on rods. It causes little or no ability to distinguish colors.
Cone cell : A retinal photoreceptor that supports daylight vision and color discrimination. Monochromacy follows when only one cone class functions or cone signaling is absent.
Trichromacy : Color vision based on comparing signals from three classes of cone photoreceptors. It is the usual human arrangement that monochromacy departs from.
Electroretinography : A test that records the retina’s electrical response to flashes of light. It can reveal whether cone responses are absent or selectively preserved.
Dichromacy : Color vision based on two functioning cone classes rather than the usual three. Dichromacy preserves two cone signals, unlike monochromacy’s single or absent cone class.
Rod cell : A retinal photoreceptor specialized for vision in dim light, with little role in color discrimination. In rod monochromacy, rods provide the principal visual signal.
Retina : The light-sensitive tissue lining the back of the eye, containing photoreceptors and neural circuits. Monochromacy originates in the retinal signals that feed visual processing.
Color vision test : A clinical assessment of the ability to identify or match colors. Testing characterizes color discrimination but must account for monochromacy’s visual limitations.
Anomalous trichromacy : A form of color vision deficiency in which all three cone classes function, but one has an altered spectral sensitivity. It usually weakens color discrimination without reducing vision to one functioning cone class.
Photopsin : A light-sensitive pigment in cone cells, tuned to a range of wavelengths. Differences among cone photopsins normally provide the signals needed to distinguish colors.
L-, M-, and S-cones : The three human cone classes, most sensitive to long, medium, and short wavelengths respectively. Their relative signals normally enable color discrimination that monochromacy disrupts.
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