Hypertelorism

Original article contributed by:	Pedro.A.Silva; Marta.C.E.Guedes
All contributors:	Cat Nguyen Burkat, MD FACS and Pedro A. Silva, MD
Assigned editor:	Richard Scawn, MD, FRCOphth
Review:	Assigned status Update Pending by Richard Scawn, MD, FRCOphth on October 21, 2017.

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Hypertelorism
Classification and external resources
ICD-10	[1]75.2

Orbital Hypertelorism (ORH) is an abnormally increased distance between the orbits, and it can also be associated with dystopia. It can be unilateral or bilateral, symmetric or asymmetric, and associated with conditions like craniofacial dysplasia, encephaloceles and craniosynostosis syndromes . When indicated for esthetical reasons, treatment involves surgery. ORH should not be confused with telecanthus, in which the distance between the pupils is normal.

Disease Entity

• ICD 10: Q75.2 - Hypertelorism

Disease

The ORH is a true lateralization of the orbit where the inner canthal distance (ICD), the outer canthal distance (OCD) and interpupillary distance (IPD) are increased (figure 1). It is a manifestation of a craniofacial deformity and not a disease in itself .

Figure 1 – Increased ODC, IPD and ICD in ORH.

Etiology

ORH can be seen in a variety of conditions such as craniofacial clefts, craniofacial dysplasias and craniosynostosis syndromes, like Edwards Syndrome, 1q21.1 Duplication Syndrome, Basal Cell Nevus Syndrome, DiGeorge Syndrome Loeys-Dietz Syndrome, Apert Syndrome, Noonan syndrome, Neurofibromatosis, Leopard Syndrome, Crouzon Syndrome, Wolf-Hirschhorn Syndrome, Andersen–Tawil Syndrome, Waardenburg Syndrome and Cri-du-Chat Syndrome.

Embryology

In ORH, there is a defective movement of the orbit towards midline. Purposed mechanisms include a defective development of the nasal capsule, deficient latero-medial movement of the orbit, early ossification of the lesser wings of sphenoids and a frontonasal prominence that remains in its embryonic position.

Differential diagnosis

Telecanthus, also known as Pseudo-hypertelorism, is an entity in which the ICD is increased but the OCD and IPD are unchanged. Some Congenital disorders such as Down Syndrome, Fetal Alcohol Syndrome, Cri-du-Chat Syndrome, Klinefelter Syndrome, Turner Syndrome, Ehlers-Danlos Syndrome and Waardenburg Syndrome can be associated with Telecanthus.

General treatment

Treatment involves corrective surgery and is indicated primarily done for esthetical reasons. The aim is to bring the orbits medially and correct any orbital dystopia or any soft tissue blemishes.

Surgery

When indicated, the surgery is performed between 5 - 7 years old to avoid any injury in the un-erupted tooth roots and maxillary growth disturbances. There are two operative techniques: box osteotomy and facial bipartition (figure 2). The first one involves an en-bloc movement of the orbits medially into the space created by resection of abnormally wide nasal and ethmoidal bones. A midline excision of skin is frequently necessary due to the excessive skin created. This technique is performed when dental occlusion is normal. The facial bipartition involves a medial resection of the nasal dorsum in a “V” shaped form, a split in the midline of the palatal bone and a medialization of the two hemifaces. This technique is performed when there are associate dental arch deformities. For a better esthetical result, it is also important to take soft-tissue reconstruction in consideration. It is also important to consider a medial canthopexy for better results.

Figure 2 – A: Box osteotomy; B: Facial bipartition.

Complications

The main complications of both surgeries for ORH correction include excessive bleeding, risk of infection and cerebrospinal fluid leaks. Rare events also include blindness, visual disturbances, ptosis and diplopia.

References

2. Jackson, T. L.; Moorfields: Manual of Ophthalmology; London, U.K.; Mosby Elsevier, 2008.