Achromatopsia is a congenital cone dystrophy characterized by a complete absence of functional cones in the retina. In infancy, patients present with poor visual acuity, pendular nystagmus, severe photophobia, and a complete lack of color perception. Visual acuity generally stabilizes around 20/200, however, nystagmus and photophobia may improve slightly with time.
In the US, achromatopsia occurs with an estimated prevalence of less than 1 in 30,0000. Diagnosis of achromatopsia is based on medical history, color vision testing, and electrophysiologic examination. Genetic testing can confirm the diagnosis. There is no treatment to cure achromatopsia, but in those affected, the remaining vision can be enhanced using different aids. Dark brown or red tinted sunglasses help reduce light intensity and maximize the function of the rods during the day.
Achromatopsia is inherited in an autosomal recessive manner. There are four different genes implicated in the development of different forms of achromatopsia. The CNGA3 (Cyclic Nucleotide Gated Channel, Alpha-3) gene on chromosome 2q is involved in the pathogenesis of achromatopsia 2.
