| Axenfeld-Rieger Syndrome Signs and Symptoms
Patients displaying Axenfeld-Rieger (A-R) syndrome are generally
asymptomatic. The condition is diagnosed based upon findings from routine biomicroscopic
and gonioscopic evaluation. Historically, this condition was incorporated under the
broader heading of anterior chamber cleavage syndromes, and included Axenfeld’s
anomaly, Axenfeld’s syndrome, Rieger’s anomaly, and Rieger’s syndrome.
Current theory now holds that these conditions are probably a continuum of a single
developmental disorder, hence the name Axenfeld-Rieger syndrome.
This anterior segment disorder always presents with posterior
embryotoxon (a prominent, anteriorly displaced Schwalbe’s line) and one or more of
the following findings: iris strands adherent to Schwalbe’s line, iris hypoplasia,
focal iris atrophy with hole formation, corectopia, and ectropion uveae. Glaucoma may
develop in approximately 50 percent of patients with A-R syndrome, but is more common in
those with central iris changes and pronounced anterior iris insertion. Non-ocular
manifestations of A-R syndrome may include developmental defects of the teeth and facial
bones, pituitary anomalies, cardiac disease, oculocutaneous albinism, and redundant
periumbilical skin. A-R syndrome is always bilateral but may be markedly asymmetric. The
condition appears to be hereditary, displaying an autosomal dominant inheritance pattern
with variable expression.
Pathogenesis
There has been much speculation as to the embryonic pathogenesis of A-R
syndrome. The current and most widely held theory suggests a developmental arrest of
specific anterior segment tissues derived from neural crest cells, which apparently occurs
late in gestation. It is not understood why such a developmental arrest occurs, but the
result is the retention of a primordial endothelial cell layer on portions of the iris and
angle structures. Contraction of these endothelial "membranes" leads to the
associated abnormalities in form and function of the anterior segment structures.
Presumably, this same developmental arrest can affect other organ systems, resulting in
orofacial and other anomalies sometimes encountered in A-R syndrome.
Management
A-R syndrome, a congenital disorder, generally requires little therapeutic
intervention. In those instances where iris atrophy results in pseudopolycoria, patients
may be fitted with opaque, cosmetic contact lenses to improve their appearance and
decrease optical aberrations.
The greatest concern in patients with A-R syndrome is the development of
secondary glaucoma. In most cases, those who develop glaucoma do so in childhood or early
adulthood. Still, patients must be monitored throughout life for elevations in intraocular
pressure and optic nerve head changes. Glaucoma therapy for patients with A-R syndrome
follows the same therapeutic algorithm as for primary open angle glaucoma, however miotics
are reported to be less effective in this condition. Typical therapy begins with topical
-blockers (e.g., Betoptic-S) or topical carbonic anhydrase inhibitors (e.g., Azopt).
Unfortunately, many of these glaucoma cases become recalcitrant, and surgical intervention
is often necessary.
Clinical Pearls
Axenfeld-Rieger syndrome is described as a rare,
congenital ocular disorder. Still, these authors have encountered many patients with
manifestations of A-R syndrome, some of which are exceedingly subtle. In general, A-R
syndrome is more academically interesting than it is clinically challenging. Glaucoma must
be a concern in every patient presenting with this disorder. In fact, when glaucoma does
occur, it can be quite severe. In addition, patients with A-R syndrome should undergo both
a comprehensive medical and dental evaluation to rule out non-ocular manifestations.
Because of the known inheritance pattern and variable
expression, recommend ocular evaluation for all family members when you detect A-R
syndrome.
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