Abnormal Interocular Distance: Terminology and Associations
Telecanthus is characterized by a greater-than-normal distance between the inner canthi; it is distinct from, but may accompany, orbital hypertelorism (excessive distance between the medial orbital walls). In primary telecanthus, the abnormality is confined to the soft tissue, occurring without hypertelorism: the interpupillary distance is normal (see also Chapter 17 and Fig 17-1). When telecanthus is secondary to hypertelorism, the interpupillary distance is greater than normal. Telecanthus is common in many syndromes.
Orbital hypotelorism is smaller-than-normal distance between the medial orbital walls, with reduced inner and outer canthal distances. The finding is associated with more than 60 syndromes. Hypotelorism can be the result of skull malformation or a failure in brain development.
Exorbitism is variously defined as prominent eyes due to shallow orbits or as an increased angle of divergence of the orbital walls.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.