Achromatopsia is an inherited retinal disorder that causes extreme sensitivity to light (ie, daytime blindness) and reduced visual acuity and color discrimination. Color blindness is caused by mutations in one of several genes.

To ensure weather you are affected with Achromatopsia(Color blindness), you have to do color blind test.

There is common genes that associated with the disease are the CNGA3 and CNGB3 genes; Mutations with these can cause about 75% of cases.

Achromatopsia(Color blindness)is caused by mutations in one of a few genes.The genes most commonly associated with the disease are the CNGB3 and CNGA3 genes- Mutations in these cause about 75% of cases.

Mutations in GNAT2, PDE6C, and PDE6H also are able to cause the disease. Congenital achromatopsia is an inherited eye condition that more or less negatively affects the development of the retinal "cones"; The cones are photoreceptor cells that convert light into electrical images that are transported to the brain and interpreted as visual images.

The cones work in bright light and are responsible for color perception, sharp visual acuity (seeing details) and central vision. Achromatopsia(Color blindness) is a stable eye condition (meaning it will not progress to a worsening vision condition).

Achromatopsia

People with achromatopsia are totally color-deficient, Dr. Layman says. This means they can only see things as black and white or in shades of gray.

Unlike other forms of color blindness, this condition is usually connected to a larger type of eye problem, says Jeffrey Dello Russo, MD, an ophthalmologic surgeon in New York City.

For example, people with achromatopsia can have additional vision issues like:

• increased light sensitivity
• involuntary, rapid eye movements (either side-to-side, up and down, or in a circular motion)
• low visual acuity, or difficulty seeing things clearly
• Some people with achromatopsia also have farsightedness or nearsightedness, according to the U.S. National Library of Medicine.

It’s the rarest form of color blindness, however, affecting about 1 in 30,000 people worldwide.

Symptoms

Achromatopsia causes extreme light sensitivity (i.e., day blindness), as well as reduced visual acuity and color discrimination.

People with the condition wear glasses with tinted lenses to filter out the type of light that is uncomfortable. Different patients have different light-filtering needs.

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.

Inheritance

Achromatopsia is caused by mutations in one of a few genes. The most common genes associated with the condition are the CNGB3 and CNGA3 genes — mutations in these cause about 75 percent of cases.

Mutations in GNAT2, PDE6C, and PDE6H can also cause the disease.The condition is passed down through the autosomal recessive inheritance pattern.

In autosomal recessive diseases, both parents carry one copy of the mutated gene and one normal copy, but have no symptoms themselves. They are therefore referred to as unaffected carriers.

Each of their children has a 25 percent chance of being affected by inheriting a mutated copy from each parent. If the child inherits one mutated copy from one parent, they will be an unaffected carrier.

Living with the Disease

There are many services and accommodative and assistive resources available to people and families with achromatopsia.

American Printing House ConnectCenter

The APH ConnectCenter provides resources and information to people who are blind and low vision, their families and professionals in the field.

Duke Eye Center: Vision Rehabilitation and Performance

The Duke Vision Rehabilitation and Performance Division at Duke Eye Center may be the best in the country, and one of only two in the southeast US. Led by Diane Whitaker, OD, Duke's state-of-the-art vision rehabilitation center and occupational therapy program helps patients with vision loss manage day-to-day activities with training, tools, and therapy. 

The Low Vision Shop is a one-stop-shop for all assistive devices for low vision and blindness, including the latest in wearable technology.

We are proud to be the go-to source for best-in-class low vision and blind assistive devices online, in our physical stores in the Baltimore area, South Florida and New York, and with multiple B2B channels.

Genetic Testing

It helps assess the risk of passing the disorder from parent to offspring. It also helps with attaining an accurate diagnosis. A patient with an accurate diagnosis is in a better position to understand which emerging treatment approaches and clinical trials are most appropriate for them.

Why Genetic Testing is Important?

An Overview of Genetic Testing for Inherited Retinal Diseases (IRDs)

Most rare retinal diseases – including retinitis pigmentosa, Stargardt disease, Usher syndrome and choroideremia – are inherited and usually caused by one or more defects (mutations) in a single gene. 

Genetic testing is available to attempt to identify the defective gene causing the IRD in an individual or family.  

There are potential benefits to knowing the underlying genetic cause of a person’s IRD. It may help confirm or refine a diagnosis. Knowing the mutated gene can help a person understand how the disease may affect their vision during their lifetime.

It can also guide the testing of family members to identify those at risk of inheriting the condition. Knowing the genetic defect may help people qualify for clinical trials and inform them about which future therapies may be of benefit. 

At the same time, the information revealed from a genetic test may not be immediately helpful to an individual or family.  In some cases, the knowledge might create anxiety for some family members. 

It is very important to remember, however, that a genetic test may not reveal the defective gene, which can be frustrating for a patient and their family. 

The decision to undergo genetic testing should not be made lightly. Anyone interested in a genetic test is strongly advised to talk to a genetic counselor or retinal physician who is knowledgeable about the genetic testing process and the potential impacts of the results, before they decide to undertake the test. 

The Genetic Testing Process

Get a Thorough Clinical Exam — Before blood is sent off to a laboratory for testing, a patient needs to get a thorough clinical exam conducted by a retinal specialist familiar with IRDs.

Usually, a clinical exam will give a strong indication of what the disease is — e.g., Stargardt disease versus retinitis pigmentosa.

This can greatly help the genetic testing lab narrow the scope of the search for the disease-causing gene mutation, saving time and money.

Meet with a Genetic Counselor — Genetic counseling is a critical part of the genetic testing process. A genetic counselor can help you decide if genetic testing makes sense for you and your family.

A genetic counselor can also help determine the best genetic test for you, based on current test methodology, number of genes to be tested, detection rate, price of the test, and potential insurance reimbursement.

The counselor can also tell you the likelihood that the genetic basis of your condition will be found and how discovering, or not discovering, the genetic defect might affect you and your lifestyle.

In addition, he or she will interpret the test results for you, and serve as your advocate throughout the genetic testing process.

3. Submit a Blood Sample — The genetic testing lab will provide instructions for the doctor or clinical lab drawing the blood sample, including how much blood is required and where the sample should be sent. Getting blood drawn for a genetic test is not much different from getting blood drawn for other common tests.

Receive and Interpret Results — It can take several months for initial results to come back from a genetic testing lab. Sometimes the disease-causing gene is not found.

The likelihood of finding the gene depends on several factors which your genetic counselor can discuss with you.

Regardless of whether your gene mutation is found, your genetic counselor will help you understand the results and recommend next steps. In some cases, re-testing may be an option, perhaps at a later date.

Costs of Genetic Testing and Counseling — The costs associated with genetic testing and counseling can vary depending on who is providing the services and what disease is being investigated.

Some insurance companies will reimburse for these expenses — others won’t. If the expense is a concern, talk with your genetic counselor before you begin the process.

He or she should be able to give you an estimate of how much the counseling will cost and whether your insurance will cover it.

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), 
• 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.