Summary Card
Definition
An increase in the interorbital distance between the dacryons.
Classification
Tessier classification is based on interorbital distance. The standard is 20-30mm.
Causes
Syndromic (Apert's, Crouzens, Edwards) or non-syndromic (facial clefts, midline tumours).
Management
An MDT to restore orbital dystopia and cosmesis through box osteotomy, facial bipartition, and medial canthopexy.
Definition of Hypertelorism
Hypertelorism is an increase in the interorbital distance as measured between the dacryons. It results in true lateralization of the orbit where the inner canthal distance (ICD), the outer canthal distance (OCD) and interpupillary distance (IPD) are all increased.
It is a congenital condition caused by overexpansion of ethmoid sinuses.
Classification of Hypertelorism
Hypertelorism is a measurement from the dacryon. This is the junction between the maxillary, frontal and lacrimal bones. It is a radiological measurement, not a clinical measurement.
The average adult interorbital distance can range from 20-30mm. Tessier provides a classification of this, as detailed below in the illustration.
It is important to be aware of two other similar conditions:
- Telecanthus: increases the intercanthal distance with the normal distance between the bony orbits.
- Pseudo-hypertelorism: 'illusion' of telecanthus in patients with a flat nasal bridge or prominent epicanthal folds. This is linked to Down Syndrome, Fetal Alcohol Syndrome, and Klinefelter Syndrome.
Causes of Hypertelorism
Hypertelorism can be syndromic or non-syndromic:
- Syndromic: Apert's, Craniofrontonasal dysplasia, Crouzens, Edwards
- Non-syndromic: Sincipital encephaloceles, facial clefts, midline tumours
An example of hypertelorism is seen in the illustration below of a patient with craniofrontonasal dysplasia.
Management of Hypertelorism
The management of hypertelorism is centred on a multi-disciplinary team. The goal of treatment is to restore function, normal orbital dystopia, cosmesis and normal anatomical alignment.
Surgical techniques that can be considered are:
- Box Osteotomy: normal midface width and hypertelorism
- Facial Bipartition: an inverted V deformity of maxillary occlusion.
- Medial Canthopexy: reattach the medial canthal ligament after osteotomies
Surgery is often indicated between the ages of 5 - 7. This is to reduce the risk of damage to unerupted teeth or maxillary growth.
These surgical treatments for hypertelorism are visualised below.
