Color blindness may be an inherited condition or may come from diseases which affect the optic nerve and the retina.
The acquired color blindness appears only in the affected eye and may be worse over time. Patients who have color blindness due to other diseases usually have problems in the separation of blue or yellow.
The inherited color blindness is more common. It affects both eyes and does not deteriorate over the years. The incidence of this type is 8% in men and 0.4% in women. This type is associated with X chromosome and in almost cases is transferred from mother to her son.
The color blindness may be partial and called dyschromatopsia (affects only certain colors) or full (all colors are affected). Complete color blindness is extremely rare. These patients usually have also other eye problems.
The photoreceptors called cones allow us to perceive colors.
These are located in the central region of the retina and contain three photosensitive pigments: the red, the green and the blue. Those who have color blindness problem have partial or complete lack in one or more of these three pigments.
Patients who have normal color perception are also called trichromatic. On the other hand, patients who have dyschromatopsia and lack of a pigment are called anomalous trichromatic. A dyschromatic patient has absolute lack of cone pigment.
Color blindness symptoms
Color blindness symptoms depend on various factors, such as whether the problem is congenital or acquired, partial or total.
• Difficulty in recognizing red and green (most common case)
• Difficulty in recognizing blue and green (less common case)
The symptoms of more serious inherited problems of color blindness and of some types of the acquired condition may be:
• Objects may appear in different shades of gray (this appears in full color blindness and is very rare)
• Decreased visual acuity