What are the other Names for this Condition? (Also known as/Synonyms)

• Areolar Atrophy of the Macula
• CACD (Central Areolar Choroidal Dystrophy)
• Central Areolar Choroidal Sclerosis

What is Central Areolar Choroidal Dystrophy? (Definition/Background Information)

• Central Areolar Choroidal Dystrophy (CACD) is an inherited disorder that affects the choroid and retina, which are parts of the eye. It is classified as a type of hereditary macular disorder. CACD causes macular atrophy of choroid and retina resulting in a set of associated signs and symptoms
• Even though it is a congenital condition, the onset of signs and symptoms generally occur during middle-age. The condition is progressive in nature and can lead to total blindness
• The cause of Central Areolar Choroidal Dystrophy is a mutation in the PRPH2 gene that leads to atrophy of the eye parts. Since, the condition is inherited, a positive family history is a key risk factor
• Central Areolar Choroidal Dystrophy results in signs and symptoms that include night vision difficulties and loss of central vision. The condition is progressive and ultimately results in total vision impairment
• A healthcare provider can use various physical (eye) exams, blood tests, and imaging studies to diagnose Central Areolar Choroidal Dystrophy. Currently, there is no treatment available to manage the condition and the prognosis of CACD is typically poor

Who gets Central Areolar Choroidal Dystrophy? (Age and Sex Distribution)

• Central Areolar Choroidal Dystrophy is a congenital condition that is manifested at birth. However, the onset of signs and symptoms occur in the ages between 30-50 years
• The condition affects both males and females
• Individuals of different racial and ethnic backgrounds can be affected
• The prevalence of CACD is between 1 in 10,000 to 1 in 100,000

What are the Risk Factors for Central Areolar Choroidal Dystrophy? (Predisposing Factors)

• The main risk factor for Central Areolar Choroidal Dystrophy is a positive family history

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Central Areolar Choroidal Dystrophy? (Etiology)

Central Areolar Choroidal Dystrophy is a congenital disorder that is inherited in an autosomal dominant/recessive manner. It is also classified as a type of choroidal dystrophy.

• Mutations in the PRPH2 gene have been identified as the cause of Central Areolar Choroidal Dystrophy
• Some mutations in the PRPH2 gene are autosomal dominant, while others are autosomal recessive
• CACD causes macular atrophy of choroid and retinal pigment epithelium (RPE) resulting in the signs and symptoms of the condition

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Central Areolar Choroidal Dystrophy?

The signs and symptoms of Central Areolar Choroidal Dystrophy are observed in young and middle-aged adults (mean age of symptom onset is 46 years). It may vary from one individual to another and is a progressive condition. The signs and symptoms that are caused due to damage of macula of eye may include:

• Difficulty in night vision or dim-light vision (nyctalopia)
• Loss of central vision
• Gradual loss of vision
• The condition affects both the eyes (bilateral presentation)

The signs and symptoms of some individuals progress more rapidly than others. Depending on the progression of signs and symptoms and findings in the eye, Central Areolar Choroidal Dystrophy is classified into 4 stages:

• Stage 1 Central Areolar Choroidal Dystrophy, with mild signs and symptoms
• Stage 2 Central Areolar Choroidal Dystrophy, with moderate signs and symptoms
• Stage 3 Central Areolar Choroidal Dystrophy, with severe signs and symptoms
• Stage 4 Central Areolar Choroidal Dystrophy, with advanced and severe signs and symptoms

How is Central Areolar Choroidal Dystrophy Diagnosed?

A healthcare professional may diagnose Central Areolar Choroidal Dystrophy using the following tests and procedures:

• Physical examination and analysis of previous medical history
• Eye examination by an eye specialist
• Fundoscopic (ophthalmoscopic) examination by an eye specialist, who examines the back part of the eye (or the fundus)
• Visual acuity test using a special and standardized test chart (Snellen chart)
• Slit-lamp examination: Examination of the eye structure using a special instrument called a slit-lamp. In this procedure, the pupils are dilated and the internal eye structure is examined
• Tonometry: Measurement of intraocular pressure or eye fluid pressure, especially to detect conditions such as glaucoma
• Fundus fluorescein angiography (FFA): In this technique, the eye blood vessels are examined using a fluorescein dye
• Fundus autofluorescence (FAF) imaging: It is a diagnostic technique to examine the fundus of the eye using a fluorescent dye
• Indocyanine green (ICG) angiography: It is used to examine the blood vessels of the choroid using a dye, called indocyanine green, particularly to study the choroid
• B-scan ultrasonography: Special ultrasound scan of the eye through a non-invasive diagnostic tool, to assess health of the eye structures
• Electroretinogram (ERG): It is a technique to measure electrical activities in the retinal cells
• Optical coherence tomography (OCT) of eye: Radiological imaging technique to visualize the eye structure
• Blood tests that include:
  • Complete blood count (CBC) with differential
  • Erythrocyte sedimentation rate (ESR)
  • Testing for PRPH2 gene mutation on a blood sample

Note: CACD is often misdiagnosed as age-related macular degeneration.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Central Areolar Choroidal Dystrophy?

The complications of Central Areolar Choroidal Dystrophy may include:

• Retinal detachment: An eye condition wherein the retina gets separated from the eye structures that holds the retinal layers together
• Total blindness due to progression of the condition

How is Central Areolar Choroidal Dystrophy Treated?

• Currently, there is no definitive treatment modality available for Central Areolar Choroidal Dystrophy
• Symptomatic treatment to address the signs and symptoms may be employed by the healthcare provider
• Rehabilitation, vocational, or occupational therapy may be provided to the affected individuals with vision loss

The healthcare provider may recommend the best treatment options based upon each individual’s specific circumstances.

How can Central Areolar Choroidal Dystrophy be Prevented?

• Currently, there are no specific methods or guidelines to prevent Central Areolar Choroidal Dystrophy, since it is a genetic condition
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as Central Areolar Choroidal Dystrophy

What is the Prognosis of Central Areolar Choroidal Dystrophy? (Outcomes/Resolutions)

• The prognosis of Central Areolar Choroidal Dystrophy is poor. CACD leads to complete vision loss by the time an individual reaches the age of around 60-70 years
• Even though the prognosis is generally poor, it also depends upon the rapidity of progression of the signs and symptoms. Individuals with slowly advancing conditions have slightly better outcomes than those with rapidly advancing CACD

Additional and Relevant Useful Information for Central Areolar Choroidal Dystrophy:

Please visit our Eye & Vision Health Center for more physician-approved health information:

http://www.dovemed.com/health-topics/vision-center/