A recent global survey shows achromatopsia remains relatively misunderstood and underdiagnosed, and individuals with this disease face a difficult journey in pursuit of an early and accurate diagnosis.
In 1997, a book published by neurologist Oliver Sacks, MD, “The Island of the Colorblind,” revealed an unusual trait in the inhabitants of the small Micronesian island of Pingelap—they were born completely colorblind. Known on the island as maskun, which literally translates as “not see” in Pingelapese, the rare genetic disorder is better known as achromatopsia by the rest of the world.
Achromatopsia is an autosomal recessive disease that affects approximately 1:30,000 individuals and is associated with complete loss of cone function. It is most commonly caused by mutations in the CNGB3 and CNGA3 genes and is associated with severely reduced visual acuity and extreme photosensitivity, resulting in daytime blindness.
Due to a loss of cone cell function, patients have complete loss of color discrimination. Most patients with achromatopsia have an average visual acuity of 20/200, resulting in a diagnosis of legal blindness. Profound sensitivity to light during the day results in significant impairment in visual function, and many patients cope by wearing darkly tinted glasses to lessen the effect of light sensitivity.
Even though this inherited retinal disease was the focus of a popular book by the well-known Dr. Sacks, a recent global survey conducted by Achroma Corp. shows that this disease remains relatively misunderstood and underdiagnosed, and individuals with achromatopsia face a long and difficult journey in pursuit of an early and accurate diagnosis.
In an effort to better understand and engage the achromatopsia community, the “Understanding the Achromatopsia Patient Experience” survey was conducted online in January 2018 on behalf of Achroma Corp. and in partnership with Applied Genetic Technologies Corp. (AGTC), a gene therapy company. The survey, distributed through Achroma Corp.’s network, was completed by 226 respondents who have been diagnosed with—or have a child who has been diagnosed with—achromatopsia.
Initial symptoms of achromatopsia typically appear in infancy, as this is a congenital disorder. Symptoms can include nystagmus (rapid involuntary eye movements), as well as photosensitivity and markedly reduced visual acuity.
According to the global survey, photosensitivity is reported as being the most debilitating and bothersome symptom of achromatopsia; on a 0–100 scale, adults with achromatopsia give photosensitivity a rating of 77 on severity and 75 on being bothersome.
Christine N. Kay, MD
Dr. Kay is a principal investigator in the AGTC-sponsored gene therapy trials for CNGA3 and CNGB3 achromatopsia.
1. Sharpe LT, Stockman A, Jagle H, Nathans J. Opsin genes, cone photopigments, color vision, and color blindness. In: Gegenfurtner K, Sharpe LT, eds. Color Vision: from Genes to Perception. Cambridge, UK: Cambridge University. Press; 1999:3-52.
2. Achroma Corp. announces global survey results of 226 people with achromatopsia. Achroma Corp. https://www.achromacorp.org/PatientJourney.html. Accessed June 27, 2018.