Achromatopsia

Resources and Recommendations for Achromats

What is Achromatopsia?

Achromatopsia is a genetic condition affecting roughly 1 in 30,000 individuals around the world, though the likelihood can vary depending on location. It is autosomal recessive in nature, meaning an affected gene must be inherited from both parents, who can be either a carrier or affected.

There are two types of photoreceptor cells in the retina that convert light into electrical signals, cones and rods. Achromats have little to no cone function and rely almost exclusively on rods.

Rods are

Highly sensitive to low light levels (i.e., scotopic vision).
Enable vision in dimly lit environments (night vision).
Easily saturated in bright light, thus not effective for daytime color vision.

Cones are

Less sensitive to low light than rods.
Function best in bright light (i.e., photopic vision).
Primarily responsible for color vision and high-acuity vision.

Because achromats have little to no code function, the primary symptoms are complete or partial color blindness, extreme light sensitivity (photophobia), and reduced visual acuity.

Genetic Causes and Diagnosis

The condition is most commonly caused by mutations in genes CNGB3 and CNGA3 which are involved in the retina’s cone cell function. Together, these mutations account for around 75% of cases.

Diagnosis is primarily made through clinical symptoms, genetic testing, and specialized eye exams such as electroretinograms (ERG).

Impact on Everyday Life

The primary impacts are difficulty in bright environments and challenges with color-coded tasks. Even very cloudy days and office lighting can decrease visual acuity and cause discomfort. Many achromats will attest, the light sensitivity and decreased visual acuity are the most problematic symptoms.

Though no cure currently exists, there have been gene therapy trials in recent years. Management of symptoms by wearing dark or red-tinted lenses, using low-vision aids, and environmental adaptations. Getting a good pair of sunglasses or tinted contact lenses can result in a much better quality of life.