X-linked incomplete achromatopsia is a rare cone disorder and it is an inherited form of blue color blindness. In this condition both red and green cone sensitivities are absent, however rod function and blue cone sensitivities are present. It is most commonly results either from one of two conditions. The first condition is a deletion of the locus control region (LCR) which is a critical DNA element that lies upstream of the L and M photopigment gene array on the X-chromosome and is necessary for expression of the photopigment genes. The second condition is an inactivating point mutation within the coding sequence of the remaining photopigment gene in an array from which all but one gene has been deleted.
- Reduced visual acuity (clearnes)
- Infantile nystagmus that decreases with age
- Light sensitivity
- Impaired color vision
- Blue color blindness
- Eccentric fixation
- No obvious retinal abnormalities
- Poor or no color discrimination
There is no cure for color vision deficiencies. However, certain types of tinted contact lenses may help affected individuals distinguish different colors better.