Posted on: 8 April 2016
Achromatopsia is a color vision deficiency characterized by either a partial or complete loss of color vision. Children with partial achromatopsia may be able to see some colors, while children with complete achromatopsia will only be able to see white, black and gray. This condition is also associated with other ocular symptoms and can seriously affect your child's quality of life. Here are four things parents need to know about achromatopsia.
What causes achromatopsia?
Achromatopsia is a genetic condition. It's caused by defects in the CNGA3, GNGB3 or GNAT2 genes. All of these genes play a role in the development of the cone cells—the cells in the retina that detect color—and if the genes are defective, the cone cells may not function properly, resulting in achromatopsia.
This condition is inherited recessively, which means that a child needs to inherit two copies of a defective gene—one from their mother and one from their father—to develop achromatopsia.
What are the signs of achromatopsia?
When your child is between three and six months old, you may notice that their eyes are moving erratically. This is known as nystagmus, and it's usually the first symptom of achromatopsia. You may also notice that your child is squinting or trying to look away from bright lights. The latter is known as photophobia, and it means that the light hurts your child's eyes.
As affected children get older, other symptoms may develop. Your child may be unable to learn their colors once they start school, and if they have complete achromatopsia, they may not understand the concept of colors. This condition is also associated with poor visual acuity (between 20/60 and 20/200), so you may notice signs of poor vision like not doing well in school or not being good at sports. Children usually don't know that their vision is poor, so it's important to notice signs that they may be struggling and have them evaluated by an optometrist.
How is achromatopsia diagnosed?
In babies and young children, achromatopsia can be diagnosed through genetic testing. A small amount of blood will be taken from your child's heel, and this blood will then be sent to a laboratory for analysis. Technicians will check your child's blood for the presence of defective genes, and if they are found, a diagnosis can be made.
In older children, a variety of diagnostic tests are available. These tests include the well-known color plate tests that are used to diagnose less-serious types of color vision deficiencies. Hue tests can also be performed. During a hue test, your child will need to arrange a series of colored disks into the right order; if they have achromatopsia, they won't be able to do it. Your child's optometrist can also look inside their eyes to see if the cones are abnormal.
Can achromatopsia be treated?
Currently, achromatopsia can be managed but not cured. Glasses with dark lenses or contact lenses that have a red tint can help reduce the amount of light that gets into your child's eyes, which can relieve their photophobia symptoms. Glasses or contacts can also help improve their visual acuity. If their best-corrected visual acuity is still poor, low vision aids like magnifying glasses and text-to-speech programs can make it easier for them to do their schoolwork.
Researchers are investigating gene replacement therapies that could cure this condition in the future. Gene replacement therapies have shown promise in both mice and dogs, though human studies haven't yet been able to replicate these results.
If you think your child may have achromatopsia, take them to an optometrist right away for testing. While achromatopsia can't be cured yet, treatments are available to help manage it. For more information, contact a local eye clinic like Montgomery Eye Center.Share