Achromatopsia is often associated with light sensitivity, photophobia, and glare sensitivity. Similar to other forms of color blindness, achromatopsia can be graded as incomplete (partial) achromatopsia or complete achromatopsia (total color blindness). Sometimes these are collectively referred to as types of achromatopsia, as the word “achromat” meaning “no color.” However, not all cases of achromatopsia have “no color” vision. Monochromacy and Achromatopsia describes a range of conditions that include rod-Monochromacy, S-cone Monochromacy and Achromatopsia. Eventually this yellowing also leads to cataracts that must be treated surgically. Another factor that causes reduced sensitivity to blue is the yellowing of the crystalline lens within the eye: these cells do not regenerate and over a lifetime of exposure to light, especially UV light, the lens tends to become yellow in appearance and block the transmission of blue light, interfering with color vision. Cataracts, glaucoma, and age-related macular degeneration can cause symptoms of tritan color blindness. Typically a person with a tritan-type color vision deficiency does not see blue colors well, and may have difficulty seeing the difference between blue and green. The retinal S-cone cells make up only about 1% of the approximately 6 million retinal cone cells, so when they are damaged or not functioning properly, it can easily cause a degradation to color vision. Tritan color vision is generally characterized by a reduced sensitivity in the blue-sensitive “S” cone cells. Tritan color blindness most commonly acquired later in life due to aging of the eye or a medical condition such as glaucoma and is only very rarely inherited from birth. It is also sometimes called blue-yellow color blindness. Tritan Color Blindness (“try-tan”) includes tritanomaly and tritanopia. For example, if red text is printed on a black background, it can be very hard to read because the red appears to be very dark. Another symptom specific to protan color vision deficiency is that red colors look darker than normal. Another common issue is that pink colors appear to be gray, especially if the pink is a more reddish pink or salmon color. A very common problem is that purple colors look more like blue. It is estimated that about 25% of cases of red-green color blindness are of the protan type.Ī person with protan type color blindness tends to see greens, yellows, oranges, reds, and browns as being more similar shades of color than normal, especially in low light. Protan-type CVD includes protanomaly, which is a partial shift of the L-cone, and protanopia, which is a complete shift of the L-cone. In Protan-type CVD, the spectral sensitivity of the L-cone is shifted toward shorter wavelengths, so that it does not receive enough red light, and receives too much green light compared to a normal L-cone. The “L” stands for Long Wavelength Light, which is generally seen as red light, mainly responsible for seeing red colors. Protan Color Blindness (“pro-tan”) is an anomaly of the “L” cones.
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