The retina, the rear membrane of the eye that converts the image inside the eye into neural impulses that are transmitted to the brain, contains photoreceptor cells called rods and cones. Rods, which work most well in low light and are sensitive to motion, are mostly concentrated in the periphery of the retina. Cones, which are mostly concentrated in the central macular area, are most sensitive in bright light and provide our color and detail vision. We read using the macula.
Individuals who are born with achromatopsia (lack of color vision) have cones that do not function properly, leaving them with reduced visual acuity, reduced color vision and difficulty seeing in bright light. The degree of visual impairment can vary between “incomplete achromatopsia” where some color vision is retained and visual acuity may be as good as 20/80, or “complete achromatopsia” where none of the cones are functioning, there is no color vision, and visual acuity may be 20/200 or worse.
Individuals with achromatopsia often show mild to moderate changes in the macula area of the retina. However, especially early in the disease there may be no obvious changes in the appearance of the retina.
Individuals with Achromatopsia often have a pendular oscillating movement of the eyes called nystagmus.
Symptoms of achromatopsia do not worsen over time and do not typically lead to blindness.
Researchers have discovered several genes that may cause achromatopsia, however the CNGB3 is known to cause approximately 50% of known cases.
Achromatopsia is also known as:
- Stationary Cone Dystrophy
- Rod Monochromatism
Achromatopsia affects roughly 1 in 33,000 Americans. It is most common on the remote atoll of Pingelap in Pohnpei, part of the Federated States of Micronesia in the Western Pacific. There the disease affects 4 to 10% of the population.
Physician and author, Oliver Sacks, wrote the book The Island of the Colorblind about Pingelap, the remote Pacific atoll where 4-10% of the population has achromatopsia.
There is no treatment to cure achromatopsia, but people with the disease have found ways to enhance their remaining vision. Dark brown or red sunglasses help reduce light intensity and maximize the function of the rods during the day. Tinted contact lenses may also be helpful.
Low vision care can be very effective to help individuals with Achromatopsia to lead very normal lives.
Vision loss from Achromatopsia responds very well to magnification which can makereading, seeing signs, faces, the computer, TV and even driving a possibility. There is a wide range of optical, electronic and software magnification options to address virtually every need.
Every individual with Achromatopsia should have a low vision examination by a doctor skilled in low vision rehabilitation to help identify the most appropriate options to enhance their visual functioning, academic and vocational potential and their personal quality of life.
The Achromatopsia Group: A resource center and active discussion board for individuals, families, and friends of people affected by achromatopsia.
The Achromatopsia Network: An information network for individuals and families who are affected by achromatopsia and for professionals interested in the disease. The site offers free downloads of two books in PDF format:
- Understanding and Coping With Achromatopsia
- Living With Achromatopsia
The National Institutes of Health (NIH) has in depth information about genetics, testing and other information about Achromatopsia.