Axenfeld syndrome

Overview

Axenfeld Syndrome, also known as Axenfeld anomaly, is a rare congenital eye disorder primarily affecting the anterior segment of the eye, the area that includes the cornea, iris, and the structures responsible for draining aqueous humor. It is considered part of a spectrum of disorders collectively known as Axenfeld-Rieger syndrome, with Axenfeld Syndrome being the milder form.

Axenfeld Syndrome is characterized by an abnormal, prominent line (called posterior embryotoxon) visible on the cornea, along with adhesions between the iris and the cornea. It may be associated with an increased risk of glaucoma, but typically lacks the systemic abnormalities seen in more advanced forms of the syndrome, like Rieger syndrome.

Causes

Axenfeld Syndrome is a genetic disorder caused by mutations in genes that control eye development. The most commonly implicated genes are:

• PITX2

• FOXC1

These mutations are inherited in an autosomal dominant pattern, meaning a single copy of the mutated gene from one parent can cause the disorder. However, spontaneous mutations can also occur.

Symptoms

Signs and symptoms of Axenfeld Syndrome are usually present at birth and may affect one or both eyes. The severity can vary between individuals, even within the same family.

Ocular features:

• Posterior embryotoxon: A visible white line near the edge of the cornea seen during slit-lamp examination

• Iris strands or adhesions: Thin tissue strands that connect the iris to the posterior embryotoxon

• Corectopia: Mild displacement of the pupil in some cases

• Increased intraocular pressure: May lead to glaucoma over time

Unlike Axenfeld-Rieger syndrome, Axenfeld Syndrome typically does not involve systemic symptoms such as dental, craniofacial, or abdominal abnormalities.

Diagnosis

Diagnosis of Axenfeld Syndrome is made through a comprehensive eye exam, often during childhood or adolescence.

Diagnostic evaluations include:

• Slit-lamp examination: To detect posterior embryotoxon and iris adhesions

• Gonioscopy: To examine the drainage angle of the eye and identify structural abnormalities

• Tonometry: Measurement of intraocular pressure to screen for glaucoma

• Genetic testing: Can confirm mutations in PITX2 or FOXC1 and help differentiate from related syndromes

• Family history: Often reveals similar findings in parents or siblings

Treatment

There is no cure for Axenfeld Syndrome, but treatment focuses on preventing and managing complications, especially glaucoma.

Management strategies include:

• Regular ophthalmic monitoring: Lifelong follow-up to monitor intraocular pressure and structural changes

• Medications: Topical eye drops (e.g., beta-blockers, prostaglandin analogs) to control intraocular pressure

• Laser therapy: May be used to improve fluid drainage in certain cases

• Surgical intervention: Required if glaucoma cannot be managed with medications (e.g., trabeculectomy, drainage implants)

In cases without elevated eye pressure, treatment may be limited to observation and regular checkups.

Prognosis

The long-term outlook for individuals with Axenfeld Syndrome depends largely on the development and management of glaucoma.

Prognostic points include:

• With early detection and appropriate treatment, vision can be preserved

• If glaucoma develops and is not adequately managed, vision loss may occur

• The condition is usually stable over time, with no progression to systemic disease

Genetic counseling is recommended for families with a history of Axenfeld Syndrome, especially in planning future pregnancies and understanding inheritance patterns.