A rare form of colorblindness involving atypical rod monochromatism which and causing pendular nystagmus and photophobia. Achromatopsia 2 is a condition that affects the color vision. Most people have complete achromatopsia which is characterized by a total absence of color vision (only able to see black, white and shades of gray). Rarely, affected people may have incomplete achromatopsia which is associated with some color discrimination.
- Head posture against strong light
- Undulatory nystagmus
- Absence of photopic flicker
- Nonfunctional cone pigment
- Pendular nystagmus
- Visual acuity loss
- Involuntary back-and-forth eye movements
- Increased sensitivity to light (photophobia)
- Hyperopia (farsightedness).
Achromatopsia 2 is caused by changes (mutations) in the CNGA3 gene and is inherited in an autosomal recessive manner. Transmembrane S1 Mutations in CNGA3 from Achromatopsia 2 Patients Cause Loss of Function and Impaired Cellular Trafficking of the Cone CNG Channel.
The diagnosis of achromatopsia is based on case history, color vision testing, electrophysiologic examination, and absent or only minor fundus changes.
Although color discrimination cannot be improved, treatments are available to address some of the other associated symptoms.