Hypertelorism is a physical characteristic defined by widely spaced eyes. It is not a disease itself but rather a visible sign that can be present in various underlying conditions. While it impacts facial appearance, hypertelorism alone typically does not cause vision problems.
Defining Hypertelorism
Hypertelorism describes an increased distance between the bony eye sockets, known as orbits. Clinicians measure this condition using several facial parameters, including the interpupillary distance (distance between the centers of the pupils), inner canthal distance (distance between the inner corners of the eyes), and outer canthal distance (distance between the outer corners of the eyes). For a diagnosis of true orbital hypertelorism, all three measurements typically exceed the 95th percentile for normative values based on age.
It is important to distinguish true orbital hypertelorism from other conditions that may appear similar. For example, telecanthus involves an increased inner canthal distance, but the overall orbital spacing and interpupillary distance remain normal. Pseudohypertelorism creates an illusion of wide-set eyes due to other facial features like a flat nasal bridge or prominent epicanthic folds, without actual lateral displacement of the orbits.
Genetic and Developmental Factors
Hypertelorism frequently arises from genetic mutations or developmental anomalies during fetal growth, particularly between the fourth and eighth weeks of gestation. During normal development, eye orbits initially form far apart and then migrate closer together as facial structures mature. If this process is interrupted, perhaps by premature fusion of skull bones or abnormal bone development, the orbits may remain in a more lateral position.
Various genetic syndromes and chromosomal abnormalities are associated with hypertelorism. For instance, Apert syndrome, a genetic disorder affecting skeletal development, includes wide-set eyes, premature skull bone fusion, and fused fingers and toes. Craniofrontonasal dysplasia, an X-linked condition, also presents with hypertelorism and other craniofacial abnormalities like a bifid nasal tip and craniosynostosis. Noonan syndrome, characterized by distinctive facial features and heart defects, commonly includes hypertelorism, with some studies indicating its presence in over 68% of affected individuals.
Other conditions linked to hypertelorism include Loeys-Dietz syndrome, a connective tissue disorder, and certain types of craniosynostosis syndromes like Crouzon syndrome and Pfeiffer syndrome. While hypertelorism is often part of a broader syndrome, it can also occur in isolation, though this is less common.
Diagnosis and Associated Conditions
Hypertelorism can be identified before birth through prenatal ultrasound and after birth during a physical examination. Following initial observation, imaging techniques such as computed tomography (CT) scans and magnetic resonance imaging (MRI) are used to confirm the diagnosis and assess the extent of orbital displacement. These scans provide precise measurements of the bony orbits and help determine the underlying cause.
Once hypertelorism is identified, a comprehensive medical evaluation determines if it is an isolated finding or part of a more complex syndrome. Medical professionals look for other associated conditions or symptoms that frequently accompany hypertelorism. These can include abnormalities of the nervous system, skeletal issues, heart defects, kidney problems, and other congenital anomalies. Patients with hypertelorism as part of a syndrome might also experience developmental delays, intellectual disabilities, or specific craniofacial malformations like cleft palates or abnormal head shapes.
Treatment and Support
Treatment for hypertelorism is individualized, depending on the underlying cause and severity of orbital displacement. Surgical intervention is often considered for moderate to severe cases to reduce the interorbital distance and improve facial appearance. These procedures, performed by craniofacial surgeons, reposition the eye sockets closer together and address any associated nasal or facial bone abnormalities.
Two common surgical techniques include box osteotomy and facial bipartition. Box osteotomy involves removing a section of bone between the eyes and moving the eye sockets inward. Facial bipartition, typically for more severe cases or when there are issues with the upper jaw, involves removing a triangular bone segment from the midface and rotating the facial halves inward. The timing of surgery often depends on the patient’s age and specific condition, with many procedures occurring between five and eight years old to minimize interference with dental and facial growth.
Multidisciplinary care is important for individuals with hypertelorism, involving a team of specialists such as ophthalmologists, geneticists, neurosurgeons, and speech therapists. This collaborative approach ensures that any associated medical, developmental, or functional needs are addressed comprehensively. Supportive care aims to improve overall quality of life and manage long-term health considerations.