achromatopsia

Achromatopsia is a rare inherited retinal disorder caused by dysfunction or loss of cone photoreceptors, leading to severe impairment of color vision, reduced visual acuity, and light sensitivity. Most individuals have little to no color discrimination and rely on rods for low-light vision, while cone-mediated vision remains markedly diminished or absent. Common symptoms appear in infancy or early childhood and typically include marked photophobia, involuntary eye movements (nystagmus), and poor vision that is most limiting in bright environments.

Genetically, achromatopsia is usually inherited in an autosomal recessive pattern. The condition is associated with biallelic mutations in several genes involved in cone phototransduction and signaling, most notably CNGA3 and CNGB3, which together account for a substantial proportion of cases. Other implicated genes include GNAT2, PDE6C, and PDE6H, among others. The exact gene affected influences the phenotype to some extent, but all forms share impaired cone function.

Diagnosis relies on clinical features, electroretinography showing severely reduced or absent cone responses with preserved rod responses, and genetic testing to identify disease-causing mutations. Imaging may reveal varying degrees of foveal hypoplasia or structural changes in the macula.

There is currently no cure, but management focuses on maximizing visual function and comfort. Strategies include tinted lenses to reduce photophobia, low-vision aids, and occupational adaptations. Some individuals may benefit from vision rehabilitation programs. Gene therapy approaches targeting CNGA3 or CNGB3 are under investigation, with early studies suggesting potential safety and functional gains in selected patients.