Achromatopsia is a rare inherited retinal disease that causes colour blindness and other symptoms, including severe light sensitivity (photophobia), uncontrolled eye movements (nystagmus), and reduced vision. The condition affects the light-sensitive cells in the retina at the back of the eye. When working correctly, these cells provide our colour vision and help us see in bright light.
Achromatopsia is also sometimes known as rod monochromacy or rod monochromatism. It's typically present from early childhood. There's currently no cure to treat or reverse achromatopsia, but there is research into possible gene therapy. With the appropriate support from an early age, children can learn how to manage their symptoms and live confidently with achromatopsia.
Achromatopsia and your vision
There are two forms of achromatopsia, with symptoms that differ. With incomplete achromatopsia, you can see some colours. With complete achromatopsia, colour blindness is total, so you will only see black, white and grey. Complete achromatopsia is much more common than incomplete achromatopsia (Source: Gene Reviews). As well as colour blindness, the condition can have the following symptoms:
- Poor visual acuity, meaning it's hard to see clearly. There may be a blind spot in your central vision and a reduced visual field.
- Sensitivity to bright light (photophobia), so seeing in daylight is challenging. Bright light can be uncomfortable, even painful. This is sometimes known as day blindness.
- Nystagmus, involuntary movement of the eyes. The constant eye movement with nystagmus can also affect your vision and is often noticeable to others.
- Refractive errors such as farsightedness (hyperopia) or nearsightedness (myopia).
Symptoms and severity vary between people, but achromatopsia doesn't cause total vision loss and is generally stable over time rather than progressive.
Most people with achromatopsia have inherited it. Mutations in six genes discovered so far are responsible for achromatopsia. The CNGB3 and CNGA3 genes together are responsible for most cases, but other genes involved include GNAT2, PDE6C, PDE6H, and ATF6.
There are two types of light-sensitive cells in the retina at the back of the eye. The rod cells give us our peripheral and night vision, and cone cells help us see in bright light and provide us with colour vision. When mutations occur in the genes that cause achromatopsia, the cone cells cannot work correctly. With complete achromatopsia, the cone cells don't work at all, causing vision problems including colour blindness, low visual acuity, and light sensitivity.
With incomplete achromatopsia, the cone photoreceptors still work to some extent. When there is some cone function, you may have some colour vision and fewer vision problems than complete achromatopsia.
Rarely achromatopsia can develop later in life. For example, cerebral achromatopsia can develop due to brain damage caused by a stroke. Other types of colour blindness can occur due to eye diseases, including cataracts, glaucoma, and macular degeneration.
Can achromatopsia be cured?
There's no cure for achromatopsia at the moment. Clinical trials are underway into potential gene therapy treatment to replace the faulty gene with a healthy copy.
Meanwhile, adjustments can help manage life with achromatopsia:
- Red-tinted glasses or contact lenses can help manage light sensitivity in bright light.
- Prescription glasses or contact lenses will correct refractive errors.
- UV blocking sunglasses are useful, and many people with achromatopsia wear sunglasses inside during the day.
- Visual aids and technology such as, Seeing AI (iPhone app), can help when you need to identify colours.
- Explaining the condition to friends, family, and colleagues can make it easier for them to help you.
When to get medical advice
Parents can be the first to suspect a condition that affects their child's eyes. With achromatopsia, you may notice your baby or child's eyes moving all the time, especially after three months of age, or they can seem particularly sensitive to light. If so, it's worth speaking to your health visitor or GP, who can refer your child for assessment if necessary.
Living with achromatopsia
The symptoms of achromatopsia can be challenging to live with, especially day blindness and severe colour blindness. Wearing dark glasses most of the time, including indoors, can impact your social interactions and how you relate to people.
There is plenty of support to help people living with a visual impairment, such as low vision assessments that recommend visual aids and assistive technology to make daily life easier. Find out more about living with achromatopsia and the support we provide for children with visual impairment and their families.