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

• Choroidal Dystrophies, Unspecified
• Hereditary Choroidal Dystrophies or Atrophies, Unspecified
• Hereditary Choroidal Dystrophies, NOS

What is Choroidal Dystrophies? (Definition/Background Information)

• Choroidal Dystrophies are a group of eye disorders that involve the choroid (and retina). Most of these disorders are rare and inherited genetically from the parents. They can result in vision loss and blindness
• The choroid is a portion of the uvea (part of the eye structure) that is predominantly made up of blood vessels. The choroid provides nutrients to the retina keeping it healthy
• There are a number of types of Choroidal Dystrophies and some of these include:
  • Choroideremia: It is inherited in an X-linked recessive manner and involves the tissues of the choroid and retina. Choroideremia develops due to the degeneration of small blood vessels of both the choroid and retina
  • Gyrate atrophy of choroid and retina: It is a rare, autosomal recessive disorder causing degeneration of the choroid and retina of eye
  • Central areolar choroidal dystrophy (CACD): It is an inherited disorder that affects the choroid and retina. The condition is progressive in nature and can lead to total blindness 
  • Diffuse choroidal atrophy: It is similar to CACD, but manifests a decade earlier, in young-to-middle-aged adults
  • Helicoidal peripapillary chorioretinal degeneration: It is an extremely rare inherited disorder that affects the choroid and retina, leading to atrophy of the eye parts
  • Pigmented paravenous retinochoroidal atrophy: It is a rare eye disorder that affects the choroid and retina. The condition is termed so, because there is an accumulation of pigment along the retinal vein of the eye
• The signs and symptoms depend upon the specific type and severity of the Choroidal Dystrophy; it can also vary from one individual to another. It may include vision abnormalities such as tunnel vision, night blindness, blind spots, and muscular atrophy
• A healthcare provider can use various diagnostic modalities, such as eye exams, blood tests, and imaging studies, to diagnose Choroidal Dystrophies. Depending on the type of dystrophy, the findings will vary
• Symptomatic treatment is normally provided to address Choroidal Dystrophies. And for most forms, there is established treatment currently available. In case of vision loss, individuals may be suitably rehabilitated
• The prognosis of Choroidal Dystrophies depends on the specific type of the disorder and the severity of the signs and symptoms. Early detection and adequate treatment may yield better outcomes in some cases. However, in general, the prognosis is poor

Who gets Choroidal Dystrophies? (Age and Sex Distribution)

• Choroidal Dystrophies are generally congenital in nature, although the onset of signs and symptoms may vary from infancy to adulthood. It depends upon the type of dystrophy
  • Choroideremia: The onset of signs and symptoms is seen in early childhood; a vast majority of the affected children are males
  • Gyrate atrophy of choroid and retina: The onset of signs and symptoms may occur during early infancy; many cases are reported from Finland
  • Central areolar choroidal dystrophy: The onset of signs and symptoms occur when the individual is between 30-50 years old
  • Diffuse choroidal atrophy: The onset of the signs and symptoms occur in the ages between 20-40 years
  • Helicoidal peripapillary chorioretinal degeneration: The onset of the signs and symptoms may occur during early childhood or into adulthood
  • Pigmented paravenous retinochoroidal atrophy: It is mostly seen to affect young adults
• Choroidal Dystrophies generally affects both males and females. Individuals of different racial and ethnic backgrounds can be affected

What are the Risk Factors for Choroidal Dystrophies? (Predisposing Factors)

• The key risk factor for Choroidal Dystrophies is a family history of the condition
• Some types are known to be associated with other medical conditions/disorders

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 Choroidal Dystrophies? (Etiology)

The cause of Choroidal Dystrophies is mostly genetic and varies according to the subtype. The disorder subtypes can be autosomal dominant, autosomal recessive, or X-linked recessive.

• Choroideremia is caused by CHM gene mutation, which results in an abnormal protein, known as rab escort protein 1
• Gyrate atrophy is caused by OAT gene mutation, which is responsible for making an enzyme ornithine aminotransferase
• Central areolar choroidal dystrophy is believed to be caused by mutations in the PRPH2 gene
• Diffuse choroidal atrophy is a genetic disorder of unknown cause; the gene responsible for the condition remains unidentified
• Helicoidal peripapillary chorioretinal degeneration is a genetic disorder and the gene causing the disorder is not yet identified by the researchers
• Pigmented paravenous retinochoroidal atrophy is an eye condition of unknown cause. It may be a genetic disorder, due to the presence of occasional cases of family inheritance

What are the Signs and Symptoms of Choroidal Dystrophies?

The signs and symptoms of Choroidal Dystrophies are mostly related to the eye and depend on the specific type of the condition. It is generally progressive in nature and can vary widely from one individual to another. The signs and symptoms may be mild or severe, and usually affects both the eyes.

In general, the signs and symptoms of Choroidal Dystrophies may include:

• Difficulty in night vision or dim-light vision (nyctalopia)
• Loss of vision field: Loss of central and/or peripheral vision
• Blind spots affecting the vision, or scotoma
• Alteration of color perception
• Gradual loss of vision; blurred vision
• The condition typically affects both the eyes (bilateral presentation)

Systemic signs and symptoms may be observed with some forms of Choroidal Dystrophies such as with gyrate atrophy.

How is Choroidal Dystrophies Diagnosed?

A healthcare professional may diagnose Choroidal Dystrophies using several tests and procedures. These may include the following:

• 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
• Nerve conduction studies
• MRI scan of brain, in case of neurological presentations
• Tests to detect ornithine levels in blood, urine, cerebrospinal fluid, or aqueous humor of eye: An increased level of ornithine in the body fluids may be observed
• In newborns, testing for ornithine aminotransferase activity in a fibroblast cell or lymphoblast cell
• Blood tests that include:
  • Complete blood count (CBC) with differential
  • Erythrocyte sedimentation rate (ESR)
  • Molecular studies to detect the gene mutation can help confirm the diagnosis (when possible)

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 Choroidal Dystrophies?

The complications of Choroidal Dystrophies may include:

• Retinal detachment: An eye condition wherein the retina gets separated from the eye structures that holds the retinal layers together
• Cataracts: When the lens of the eye becomes clouded and cause vision loss
• Total blindness due to progression of the condition

Based on the specific form of Choroidal Dystrophy, a gradual deterioration of vision is observed as the child grows and develops; over time, this can result in severe vision impairment.

How is Choroidal Dystrophies Treated?

Choroidal Dystrophies are complex eye disorders that require early diagnosis and adequate treatment to prevent irreversible visual impairment from taking place. Nevertheless, in many cases, there is no standard treatment protocol available to address these progressive disorders.

The recommended treatment measures (for the various subtypes) may include the following:

• Currently, there is no treatment modality available for choroideremia. The condition is progressive and terminates in a complete loss of vision
• Gyrate atrophy of choroid and retina is treated through dietary restrictions (by limiting arginine intake) and vitamin B6 therapy
• No definitive treatment is available for the following conditions. Hence, symptomatic treatment to address the signs and symptoms may be employed by the healthcare provider
  • Central areolar choroidal dystrophy
  • Diffuse choroidal atrophy
  • Helicoidal peripapillary chorioretinal degeneration
• Generally, no treatment is necessary for pigmented paravenous retinochoroidal atrophy. The healthcare provider may chose to monitor the condition and adopt a ‘wait and watch’ approach
• Rehabilitation, vocational, or occupational therapy may be provided to individuals with severe vision abnormality

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

How can Choroidal Dystrophies be Prevented?

• Currently, there are no specific methods or guidelines to prevent Choroidal Dystrophies, since these are genetic conditions
• 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

What is the Prognosis of Choroidal Dystrophies? (Outcomes/Resolutions)

• The prognosis of Choroidal Dystrophies depends upon the following factors:
  • The specific type of Choroidal Dystrophy
  • The severity of the signs and symptoms, which may vary from mild to severe
  • Response to treatment of the individual
• The prognosis of choroideremia is typically poor and the condition leads to a gradual loss of complete vision, when the individual reaches the age of around 60 years
• The prognosis of gyrate atrophy is variable and depends on several factors. The prognosis may be excellent or poor
• The prognosis of central areolar choroidal dystrophy is poor and the condition leads to complete vision loss, when the individual reaches the age of around 60-70 years
• The prognosis of diffuse choroidal atrophy is poor and the condition invariably leads to complete vision loss
• The prognosis of helicoidal peripapillary chorioretinal degeneration is guarded and depends on the severity of the signs and symptoms
• The prognosis of pigmented paravenous retinochoroidal atrophy is generally excellent in a majority of cases

Additional and Relevant Useful Information for Choroidal Dystrophies:

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

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