Hypertelorism

Excerpt

Orbital hypertelorism is an abnormally increased distance between the eyes due to true lateral displacement of the orbits. While hypertelorism can technically describe the increased spacing between any paired structures, it most commonly refers to orbital spacing. Hypertelorism can result from several disruptions in normal craniofacial development. Premature ossification of the lesser wings of the sphenoid bone can fix the orbits in a fetal position, preventing their normal medial migration. Additionally, failure of nasal capsule development can allow the primitive brain vesicle to expand into the space typically occupied by the capsule. Disturbances in skull base development, as occurs in craniosynostosis syndromes such as Crouzon or Apert syndromes, can also result in lateral displacement of the orbits.

In cases of orbital hypertelorism, anthropometric measurements reveal an increased inner canthal distance (ICD), outer canthal distance (OCD), and interpupillary distance (IPD), all typically exceeding the 95th percentile, or 2 standard deviations above the mean, of normative values. An isolated increase in ICD without lateral orbital displacement is more accurately termed telecanthus. For this discussion, the term hypertelorism will refer to orbital hypertelorism, with telecanthus addressed in the "Differential Diagnosis" section.

A comprehensive head-to-toe dysmorphology examination is essential in all patients with hypertelorism. Additional evaluation may include genetic testing, computed tomography (CT), magnetic resonance imaging, echocardiography, renal ultrasound, and other specialty evaluations based on suspected syndromes. Treatment is typically surgical and pursued for cosmetic or functional reasons, especially in severe cases. Procedures such as box osteotomy, facial bipartition, or monobloc advancement are chosen based on orbital anatomy, maxillary arch configuration, and associated craniofacial anomalies. Optimal care requires a multidisciplinary team, including craniofacial surgeons, neurosurgeons, ophthalmologists, geneticists, psychologists, and allied health professionals. Early identification, coordinated care, and personalized surgical planning are essential for improving aesthetic, functional, and psychosocial outcomes in patients with hypertelorism.