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

• Anterior Segment Dysgenesis (ASD)
• ASD (Anterior Segment Dysgenesis)
• ASDA (Anterior Segment Developmental Anomalies)

What is Anterior Segment Developmental Anomalies? (Definition/Background Information)

• Anterior Segment Developmental Anomalies (ASDA) are a wide-ranging group of genetic disorders that involve the anterior segment region of the eye. These disorders are also termed Anterior Segment Dysgenesis (ASD)
• The anterior segment anatomical region includes the cornea, lens, iris, and aqueous humor that nourishes the eye. Any disruption in the normal development of these eye (anatomical) structures result in conditions known as Anterior Segment Developmental Anomalies
• Even though there is a lot of overlapping of signs and symptoms between the conditions that form the Anterior Segment Developmental Anomalies, the cause of each condition (mostly genetic) and its associated conditions are varied
• Many of the conditions have increased intraocular pressure resulting in secondary glaucoma. A wide variety of genetic defects may be identified on molecular studies. The severity of signs and symptoms and the degree of vision loss varies from individual to individual

Anterior Segment Developmental Anomalies constitute the following disorders:

• Aniridia (iris hypoplasia)
• Axenfeld-Rieger syndrome
• Congenital hereditary endothelial dystrophy (CHED)
• Congenital iris ectropion syndrome
• Iridocorneal endothelial (ICE) syndrome
• Iridogoniodysgenesis syndrome
• Megalocornea
• Peters anomaly and Peters plus syndrome
• Posterior embryotoxon (PE)
• Posterior keratoconus
• Posterior polymorphous corneal dystrophy (PPMD, formerly CHED Type 1)
• Primary congenital glaucoma (PCG)
• Sclerocornea

Who gets Anterior Segment Developmental Anomalies? (Age and Sex Distribution)

• Most Anterior Segment Developmental Anomalies are congenital in nature; meaning, that the presentation of symptoms are noted in early childhood
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Anterior Segment Developmental Anomalies? (Predisposing Factors)

Anterior Segment Developmental Anomalies specific risk factors depend on the type of the individual condition. In general, the following risk factors are noted:

• A positive family history is an important risk factor
• Children born to consanguineous partners or spouses have the greatest risk

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 Anterior Segment Developmental Anomalies? (Etiology)

• The cause of Anterior Segment Developmental Anomalies (ASDA) depends on the specific type of ASDA. Many disorders are inherited, and the cause mostly involves genetic mutations
• In individuals with ASDA, frequent disruptions in the aqueous humor production and drainage pathways result in complications, such as increased intraocular pressure, and consequently glaucoma

What are the Signs and Symptoms of Anterior Segment Developmental Anomalies?

The signs and symptoms of Anterior Segment Developmental Anomalies may vary from one child to another, and it may be mild or severe. It specifically depends on the ASDA type.

Some of the common signs and symptoms noted include:

• Blurred vision
• Reduced vision
• Light sensitivity
• Corneal edema (fluid buildup)
• Corneal opacity (cloudiness)
• Iris hypoplasia
• Increased intraocular pressure
• A single eye or both eyes may be involved

Other systemic signs and symptoms may be noted depending on the associated conditions (if any).

How is Anterior Segment Developmental Anomalies Diagnosed?

Anterior Segment Developmental Anomalies may be diagnosed by the following observations and tests:

• Physical examination and medical history evaluation
• Assessment of the presenting signs and symptoms
• General eye exam that include:
  • 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
  • Gonioscopy, a painless eye exam using special devices
  • Visual evoked potential (VEP) test
• Laboratory tests, as relevant
• Imaging studies including CT and MRI scans of the head and neck region
• Neurological examinations
• Prenatal tests and newborn screening
• Molecular genetic testing
• Biopsy studies, if necessary

Tests and procedures to diagnose the associated condition, if any present, are important.

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 Anterior Segment Developmental Anomalies?

The complications of Anterior Segment Developmental Anomalies (ASDA) depend on the specific type of the disorder but may include:

• Emotional stress for the parents and caregivers
• Intraocular pressure leading to glaucoma; the risk for glaucoma from ASDA is around 50%
• Development of amblyopia
• Severe vision loss
• Post-treatment complications

Individuals with associated syndromes may present additional complications.

How is Anterior Segment Developmental Anomalies Treated?

Individuals with asymptomatic Anterior Segment Developmental Anomalies may not require any treatment. However, this depends on the specific form of ASDA and evaluations undertaken by the healthcare provider.

The following treatment measures may be considered:

• In some cases, the healthcare provider may undertake a wait and watch approach with periodic screening exams
• Symptomatic management
• Decrease intraocular pressure through eye drops and medications
• Surgical intervention may be necessary, including corneal transplant (keratoplasty)
• Correction of refractive errors if any, including the use of eye glasses or contact lenses
• Close follow-up and periodic visits to the healthcare provider is important

The treatment measures include treating the symptoms and managing any associated condition/disorder.

How can Anterior Segment Developmental Anomalies be Prevented?

Currently, there are no specific methods or guidelines to prevent Anterior Segment Developmental Anomalies. However, the following may be considered:

• 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 anterior segment developmental anomalies

Undertaking early and adequate treatment of any health condition(s) is important.

What is the Prognosis of Anterior Segment Developmental Anomalies? (Outcomes/Resolutions)

• The prognosis of Anterior Segment Developmental Anomalies depends on the specific type of ASDA, the severity of the condition, early intervention, and one’s response to treatment
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications. Typically, the prognosis may be assessed only on a case-by-case basis

Additional and Relevant Useful Information for Anterior Segment Developmental Anomalies:

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

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