Hypertelorism is a term used to describe an abnormally large distance between the eyes. It refers to the position of the bony orbits, the ‘eye sockets,’ in which the eyes lie, in the skull. Hypertelorism is not a diagnosis in itself; rather, it is a feature that can have many underlying causes, either due to a mass pushing the two orbits apart, a cleft in the bone between the eyes or as part of a syndrome.
When treating a child with hypertelorism, it is important to identify the underlying condition that is causing or has caused it and to assess the current and future impact on the child. We do this by having our multidisciplinary craniofacial team review the child, conducting genetic testing, as necessary, and arranging CT and MRI scans as appropriate to identify the cause and extent of the hypertelorism. Our team uses this information to plan treatment for the child to give the best long-term results.
Hypertelorism is an increase in the distance between the bony orbits, in which the eyes lie. It can be due to a variety of causes. During development as an embryo, the eyes lie widely apart and gradually move closer together. Any process that interferes with this movement, such as abnormal development of the bones of the forehead and the base of the skull, premature fusion of the bony plates of the skull or a cleft between the bones of the nose or upper face can result in hypertelorism. In addition, growths early in life within or close to the upper facial bones or bones that make up the skull can cause distortion of the area between the eyes and cause hypertelorism.
As well as the mechanical causes, syndromes such as craniofrontonasal dysplasia, Apert syndrome, Crouzon syndrome and Aarskrog syndrome can cause hypertelorism as part of the features that make up the syndrome. It is important to determine the cause of the hypertelorism prior to planning any corrective surgery, as a mechanical cause may need addressing at the same time as surgery to correct the hypertelorism. Children with syndromes may need further surgery that can also be combined with the hypertelorism correction.
As it is not a condition or diagnosis in its own right but rather a feature with many causes, types of hypertelorism can be considered both in terms of severity of the widening between the eyes, graded in terms of the distance between the bones, and in terms of the cause. It is useful to consider whether the cause of the hypertelorism is one that occurred before birth and is stable, or whether it is caused by a growth that is continuing to worsen the condition, which could cause other problems and may require early intervention.
The wide eye position usually does not cause physical problems for the child, although occasionally there can be interference with vision. Most problems are psychosocial in nature with frequent comments by peers, teasing and consequent self-image problems.
Diagnosis is by both a clinical assessment of the child and imaging of the bones of the skull, most commonly a CT scan. This will allow accurate measurements of the bones that make up the orbit, and to see whether there is an ongoing cause for the hypertelorism that needs early treatment. It will also allow planning for corrective surgery, if needed.
It is important that assessment and treatment for hypertelorism take place in the setting of a multidisciplinary craniofacial team, like we have at Children’s Health℠. The combination of in-house pediatric plastic surgeons experienced in treating complex craniofacial conditions and pediatric oral and maxillofacial surgeons together with pediatric craniofacial orthodontists, pediatric dentists and developmental psychologists is important to provide the best care for the child.
Surgery for hypertelorism involves two main techniques, box osteotomy and facial bipartition, both of which involve separating one part of the skull containing the orbit from another part of the skull, moving it into a position in which the eyes are closer together and securing it in place in the new position. Box osteotomy involves removing a piece of bone between the eyes and moving the bones containing the orbit together into the space where the first piece of bone has been removed. Facial bipartition involves removing an upside-down triangle shaped piece of bone from the area between the eyes and rotating the two halves of the upper face inward so that the eyes end up closer together. Both of these operations leave scars, but these tend to be in the hairline just in front of the top of the head, and inside the mouth. These operations can be combined with other craniofacial procedures such as distraction osteogenesis, if appropriate in certain syndromes.
Timing of surgery is important to consider, since this surgery does involve making cuts in bone and securing them in their new position. During the first years of life, the bones are not strong enough, and there is the possibility of interfering with the growth of the face as a result of surgery. When dealing with psychosocial issues in children, however, it is helpful to complete surgery by the age of 8, as this is the age when questioning of unusual features tends to turn to teasing.
Aftercare is very important in any craniofacial surgery to ensure that the intended result has been achieved, to watch for any complications from surgery and to ensure that the child develops as expected following in the years following surgery. We are most likely to recommend continued follow-up within our multidisciplinary craniofacial team.