What Is Achromatopsia?
Congenital achromatopsia is a hereditary eye condition that adversely affects the development of, to a varying degree, retinal “cones”; cones are photoreceptor cells that convert light into electrical images that are carried to the brain and interpreted as visual images. Cones work in bright light and are responsible for color perception, sharp visual acuity (detailed vision), and central vision.
Achromatopsia is a stable eye condition (meaning it will not progress into a worse visual condition).
How Is Achromatopsia Diagnosed?
The earliest signs of achromatopsia are generally extreme sensitivity/aversion to bright light and nystagmus (involuntary, repetitive darting of the eyes), both commonly recognized while the child is three to six months of age.
Poor visual acuity and decreased or absent color vision will also be present; however, these symptoms of achromatopsia are not as quickly detected by caregivers.
Diagnosis is confirmed with an ERG (electroretinogram) which observes the inactivity of the retinal cones, a retinal examination, and possibly genetic testing. As the child ages, additional testing, including a visual field test and color vision test, can be performed.
Are There Treatments for Achromatopsia?
There is currently no treatment for abnormal retinal cones.
How Would You Describe the Eyesight of One with Achromatopsia and How Will My Child Function with It?
To varying degrees, one with achromatopsia (often called an “achromat”) will have
- tremendous discomfort in bright light as well as limited or absent vision in bright light (called a “white out”),
- limited or absent color vision,
- reduced visual acuity (which may be improved with prescription glasses), and
- possible blind spots (called “scotomas”).
Your child’s teacher of students with visual impairments should perform a functional vision assessment to determine how your child uses his or her vision in everyday life and a learning media assessment to determine which senses your child primarily uses to get information from the environment. These assessments, along with an orientation and mobility assessment conducted by a mobility specialist, will give the team information needed to make specific recommendations for your child to best access learning material and his or her environment.
The main impediment to useful vision for an achromat is extreme sensitivity to bright light and glare. The environment may appear all white or lack contrast and using the eyes in such an environment will cause great discomfort. Tinted sunglasses (often red or blue) and use of a brimmed hat will provide relief to the eyes while outdoors; often slightly tinted eyeglasses will improve vision indoors. Additionally, use of non-glare surfaces (such as a chalkboard instead of a whiteboard and matte wall paint) and use of thick curtains will aid in using vision indoors.
Your child should make the most of evening outdoor exploration, play, and social activities.
Furthermore, the child will need an orientation and mobility specialist to provide instruction on using a cane (to refrain from bumping into obstacles) and using public transportation while outdoors in the daytime.
If your child has lost color vision, he or she will see the world with less vibrancy. Your child will need a system of coordinating outfits by color; color identification labels can be affixed to clothing, or complementary colors can be hung in the closet together. Simple educational accommodations will also be useful for school assignments requiring the use of color perception. Accommodations may include use of tactile variances instead of color.
If your child has lost sharp/detailed vision, it will be difficult to recognize faces and facial expressions, access information from a classroom board or wall, view a speaker or performance, read print, and perform visual tasks of fine detail, such as threading a needle. In order to best use remaining vision, your child can be taught to increase the contrast of the environment, increase the contrast of print by using a CCTV or screen-magnification software, increase print size by using a hand-held magnifier and distance-vision optical device such as a handheld telescope (called a “monocular”). Furthermore, your child should sit in a preferred seat of a room for optimal viewing, generally nearer to the speaker or chalkboard.
If your child has blind spots, it will be difficult to gather comprehensive visual information in an environment; he or she will benefit from learning visual efficiency skills such as scanning an environment in an organized manner and possibly utilizing a reverse telescope to minimize the appearance of an image in order to see its entirety within the remaining field of vision. Additionally, the individual is likely to bump into undetected obstacles; he or she should utilize orientation and mobility skills, such as the use of a cane, to travel safely.