Anterior cleavage syndrome
 

Posterior embryotoxon Axenfeld-Reiger's anomaly Peters' anomaly showing the central leucoma

Anterior cleavage syndrome or mesenchymal dysgenesis is a group of disorders characterized by abnormal development of the anterior segment especially at the irido-corneal angle. Glaucoma occurs in some of them. The three most common  types seen in the examination are: Posterior embryotoxon There is a prominent irregular ridge which lies central to the limbus. This is a posterior embryotoxon caused by an anteriorly  displaced Schwalbe's ring. Note: this finding is seen in about 8 to 30% of normal individual. Look for another pathology as it is unlikely that this sign alone will form the main finding in the examination.   Axenfeld-Reiger's syndrome There are bilateral posterior embryotoxon with iris strands attached to it. Peripheral anterior synechiae and hypoplasia of the  anterior stroma may be seen.  Note: recently Axenfeld's anomaly and Reiger's anomaly/syndrome have been re-classified as Axenfeld-Reiger's syndrome because the two conditions have many overlapping features. However, some examiners may not be aware of this and may  ask you for the differences between Axenfeld's and Reiger's anomaly (Axenfeld's and Reiger's anomaly both have posterior embryotoxon plus anterior synechiae but only in Reiger's anomaly are there iris atrophy and pupil distortion; Reiger's  syndrome is Reiger's anomaly plus dental, craniofacial and skeletal abnormalities). Look for: trabeculectomy  corectopia, ectopia uvea and polycoria abnormal denture and maxillary hypoplasia Peters' anomaly There are bilateral (80% being bilateral) central corneal opacities involving the stroma with iris adhesion at the edges of the  opacities.  Look for: trabeculectomy  small eye (microphthalmos) cleft lip/palate, craniofacial or skeletal abnormalities or evidence of congenital cardiac defects (if any of these were present, the condition is called Peters plus syndrome)

Questions:

1. How are the above conditions inherited?

Answer
Posterior embryotoxon and Axenfeld-Reiger's syndrome are usually inherited in an autosomal dominant fashion whereas Peters' anomaly may be sporadic, recessive and sometimes dominant.

2. What is a posterior embryotoxon?

Answer
It is the anterior border of the Schwalbe's line which represents the junction of the trabecular meshwork with the termination of Descemet's membrane.

3. What is the incidence of glaucoma in the above conditions?

Answer
Posterior embryotoxon alone is not associated with glaucoma.
Half of the patients (50%) with Axenfeld-Reiger's syndrome and Peters' anomaly will develop glaucoma

4. What does the mnemonic STUMPED stands for in a patient with a congenitally opaque cornea?

Answer
S- sclerocornea
T-trauma
U-ulcers as in those caused by herpes simplex
M-metabolic disorders such as mucopolysaccharidoses
P- Peters' anomaly
E- endothelial dystrophy as in congenital hereditary endothelial dystrophy
D-Dermoid

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Dental dysplasia in a patient with Axenfeld-Reiger's syndrome
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