Hypertelorism

Hypertelorism refers to an abnormal increase in distance between any two organs although some authors use the term synonymously with orbital hypertelorism meaning an abnormal increase in distance between the two eyes. The article mainly focuses on the latter. The abnormality is similar to telecanthus which means an increased distance between the medial canthi of the eyelids.

Epidemiology

Associations

While it can be an isolated anomaly, there are numerous syndromic as well as non-syndromic associations with orbital hypertelorism which include:

• aneuploidic syndromic

  • trisomy 21

  • trisomy 13

  • monosomy X-Turner syndrome

• non-aneuploidic syndromic

  • Aarskog syndrome

  • Apert syndrome ¹

  • Baraitser-Winter syndrome ⁸

  • Crouzon syndrome ¹

  • DiGeorge syndrome

  • Ehlers-Danlos syndrome

  • frontonasal dysplasia

  • Greig syndrome

  • Gorlin syndrome

  • LEOPARD syndrome

  • Loeys-Dietz syndrome (LDS) ²

  • mucopolysaccharidoses

    • Morquio syndrome

  • Neu-Laxova syndrome (NLS)

  • Noonan syndrome ⁵

  • Pfeiffer syndrome

  • Saethre-Chotzen syndrome ⁶

  • Sotos syndrome

  • Weaver syndrome

  • Wolf-Hirschhorn syndrome

• non-syndromic

  • agenesis of the corpus callosum ^ref

  • autosomal recessive osteopetrosis ⁷

  • congenital dacrocystocele ⁴

  • hypospadias ³

  • nasoethmoidal encephalocele/frontal encephalocele

There are many more associations other than those mentioned on this list. Please add and/or reference as appropriate.

Pathology

Over development of the lesser wings of the sphenoid bone may be an underlying factor.

Radiographic assessment

Ultrasound

Hypertelorism may be assessed by measuring the distance between the lateral orbital walls or the medial orbital walls. The interocular distance/diameter (IOD) and the biocular diameter (BOD) are both typically increased with hypertelorism.

Due to its associations with other conditions, detailed sonographic surveillance for other fetal anomalies is recommended if hypertelorism is seen on ultrasound.

Some indices used include:

• orbital angle index: a value >42 is suggestive of orbital hypertelorism

• interorbital-orbital index: a value >8 is suggestive of orbital hypertelorism

See also

• hypotelorism