Hypertelorism is a medical condition where the eye sockets, or orbits, are abnormally far apart. This increased separation can be a purely cosmetic feature. However, it often indicates an underlying medical factor that developed before birth.
What is Hypertelorism?
Hypertelorism is an abnormally increased distance between the bony orbits that house the eyes. This differs from telecanthus, where only the inner corners of the eyelids are widely spaced, but the eye sockets are normally positioned. In hypertelorism, the inner eye corners, outer eye corners, and pupils are all further apart than average.
Medical professionals measure these distances: inner canthal distance (ICD), outer canthal distance (OCD), and interpupillary distance (IPD). If all three measurements exceed the 95th percentile for a person’s age, it confirms a diagnosis of true orbital hypertelorism.
The condition can range in severity, from mild to more pronounced instances. It originates during the initial weeks of fetal development, typically between the fourth and eighth week of pregnancy.
Causes and Related Conditions
Hypertelorism often results from various underlying genetic syndromes or developmental anomalies. It can arise from disruptions in craniofacial bone formation during early fetal growth. For example, premature fusion of skull bones or abnormal development of the forehead and skull base can prevent eye sockets from moving to their proper position. A mass, such as an encephalocele, pushing the bones apart can also contribute to this increased spacing.
Several genetic conditions commonly feature hypertelorism. Apert syndrome, for instance, involves premature skull bone fusion (craniosynostosis) and often includes widely spaced, bulging eyes, alongside webbed fingers and toes. Crouzon syndrome also involves premature skull suture closure, presenting with wide-set eyes, bulging eyeballs, and an underdeveloped midface.
Craniofrontonasal dysplasia is a rare X-linked condition, typically affecting females more, with hypertelorism, skull asymmetry, and other skeletal or dermatological abnormalities. Frontonasal dysplasia involves abnormal head and face development, often including widely spaced eyes, a broad nose, and a vertical groove down the middle of the face.
This condition can result from specific gene mutations that disrupt facial development. Hypertelorism can also be associated with chromosomal abnormalities like trisomy 18 or trisomy 21. While it can occur in isolation, it is more commonly part of a broader set of features.
How Hypertelorism is Diagnosed
Diagnosis of hypertelorism begins with a clinical examination, where a doctor observes eye spacing. Physical measurements of the inner canthal, outer canthal, and interpupillary distances are taken and compared to age-normative values. If these measurements are significantly increased, further evaluation is recommended.
Imaging techniques provide detailed information about underlying bone structures. X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) assess the distance between bony orbits and identify associated skeletal abnormalities. A CT scan is particularly useful for surgical planning due to its precision.
Prenatal diagnosis is possible through fetal ultrasound, which can identify widely spaced eyes during pregnancy. When hypertelorism is identified, especially in newborns, genetic testing is often performed to determine if an underlying syndrome is present.
This may involve chromosome analysis or specific gene panels to pinpoint genetic mutations. A comprehensive physical examination also identifies any other congenital anomalies that might accompany the condition.
Approaches to Management and Support
Management of hypertelorism focuses on addressing the underlying cause and any associated symptoms. If the condition is part of a broader syndrome, treatment plans target the specific issues related to that syndrome.
For significant cases of hypertelorism, surgical intervention may be considered to correct the orbital position and improve both function and facial appearance. Craniofacial surgery involves complex procedures like box osteotomy or facial bipartition. Box osteotomy separates the bony orbit from the skull, moving eye sockets closer. Facial bipartition is a more extensive surgery, often performed for other facial bone structural issues, involving reshaping eye sockets, nose, and cheekbones.
These surgeries are typically performed by experienced craniofacial surgeons, often in collaboration with neurosurgeons. Individuals with hypertelorism and associated conditions often benefit from multidisciplinary care involving various specialists. This team may include geneticists, neurologists, ophthalmologists, plastic surgeons, and speech or occupational therapists. Long-term follow-up and supportive care address diverse needs throughout a person’s life.