Definition
Dyschromatopsia is an altered perception of colors. This visual alteration is associated with a functional abnormality of some specialized cells of the retina, called cones. When one or more types of cones are defective, the perception and discrimination of colors is altered.
Subjects with dyschromatopsia have a bi-chromatic vision (they see only two colors), since they cannot perceive blue, green or red-yellow light respectively. In particular, dyschromatopsias are divided into blindness and partial perception for fundamental colors:
- protanopia and protanomalia (respectively, blindness and poor sensitivity to red);
- deuteranopia and deuteranomalia (green);
- tritanopia and tritanomalia (blue).
In achromatopsia, however, the subject has no color perception, so he sees "in black and white".
An altered perception for a given color may be congenital or secondary to other pathologies. A particular form of dyschromatopsia of hereditary nature is color blindness. The acquired forms, on the other hand, are often a symptom of a lesion affecting the optical pathways, the choroid, the macula or the retina. Dyschromatopsia, for example, can occur in case of retinopathy, neuropathy or stroke that has affected the visual centers.
Disorders depend on the location of the lesion: damage to the optic nerve tends to influence the vision of red and green; if the lesion affects the retina, on the other hand, the perception of blue and yellow is compromised.
Possible Causes * of Altered color vision
- Giant cell arteritis
- Age-related macular degeneration
- Stroke
- Cerebral ischemia
- Optic neuritis
- Retinitis pigmentosa
- Retinoblastoma
- Diabetic retinopathy
- Corneal ulcer
