Facial Bipartition

Facial Bipartition

Jessica A. Ching

Christopher R. Forrest


  • The degrees of hypertelorism may be measured using soft tissue and bony landmarks.

  • The dacryon is the most medial portion of the bony orbit, lying at the intersection of the frontal, lacrimal, and maxillary bones. This is the most common landmark for measuring interorbital distance (IOD).

  • Important bony landmarks are used to measure the inner canthal distance (ICD) between the two medial canthi measured at the level of the posterior lacrimal crest and the outer canthal distance (OCD) measured between the two lateral canthi.

  • The interpupillary distance (IPD) between the two midpupillary regions in front gaze is a useful measure, but taken by itself, increased IPD may not be indicative of hypertelorism. It may be seen in post-traumatic cases or in cases of exophoria due to extraocular muscle imbalance.

  • ICD, OCD, and IPD are always increased in cases of true hypertelorism (FIG 2).

  • Hypertelorism exhibits an increased IOD due to intervening excess bone and soft tissue.

    FIG 2 • Graphic representation of orbital measurements in the normal orbit, telecanthus, and orbital hypertelorism. ICD, inner canthal distance; OCD, outer canthal distance; IPD, interpupillary distance; PFL, palpebral fissure length. (Redrawn from Sharma RK. Hypertelorism. Indian J Plast Surg. 2014;47(3):284-292.)

    • IPD will be increased, and orbital aperture dimensions (height and width) are usually normal.

    • For children, the average interorbital distance increases with age3:

      • 1 year old: 18.5 mm

      • 2 years old: 20.5 mm

      • 3 years old: 21 mm

      • 5 years old: 22 mm

      • 7 years old: 23 ± 4 mm

      • 10 years old: 25 ± 2 mm

      • 12 years old: 26 ± 1 mm

    • For adults, average interorbital distance is 25 mm in women and 28 mm in men.3

    • Degree or severity of hypertelorism is graded in children and adults by the amount of deviation from the average interorbital distance (Table 1).


  • During embryologic development, lateral optic placodes move medially during weeks 5 to 9 and become the orbits and associated ocular structures.

  • A persistent divergence of the orbital axes reflects early developmental arrest.

  • Mechanisms of arrest include the following:

    • Deficient growth affecting the brain and eyes

    • Deficient closure of the rostral neuropore with the development of sincipital encephaloceles

    • Deficient differentiation of the nasal capsule

    • Compensatory accommodation of the cranial base to the growing brain

  • Hypertelorism may result from syndromic and nonsyndromic etiologies, such as

    • Encephalocele (nasofrontal, nasoethmoidal, naso-orbital, and combined)

    • Craniofrontonasal dysplasia

    • Median facial clefting or frontonasal dysplasia

    • Syndromic craniofacial dysostoses (ie, Apert, Crouzon, Pfeiffer)

    • Tumors

    • Vascular malformations

Table 1 Severity of Hypertelorism Defined in Children and Adults

Degree of Hypertelorism


Adultsb (Gunther’s Classification)4


2-4 mm

30-34 mm


4.1-8 mm

35-40 mm


>8 mm

>40 mm

a Reported as distance of deviation from average interorbital distance by age.

b Reported as absolute interorbital distance.


  • Hypertelorism may remain stable or worsen with growth, depending on the etiology, but it does not improve over time.

  • Relapse is common when surgery is performed in young children (under 8 years of age).


  • The preoperative evaluation includes assessment of prenatal and birth history, general development, medical diagnoses, genetic findings, family history of similar conditions, the level of patient’s and parents’ concern regarding the hypertelorism, psychosocial issues, and eagerness to undergo surgical correction for hypertelorism.

  • A history of sleep disordered breathing may suggest the need for a frontofacial advancement to increase the size of the airway.

  • Previous intracranial surgical history is important to document including cranio-orbital reshaping and insertion of a VP shunt.

  • Physical examination: a basic examination of the head and neck is mandated with specific attention paid toward the cranio-orbital and midface region.

  • Soft tissue measurements including ICD, OCD, and IPD are documented recognizing that soft tissue intercanthal measurements can be increased greater than 10 mm over underlying bone measurements.5

  • Presence or absence of midface and zygomatic hypoplasia

    FIG 3 • A technique to determine whether a camouflage or medial wall procedure would be of benefit. Placing the hand in front of the medial naso-orbital region highlights the discordance of the lateral orbital regions. A,B. This patient looks abnormal with the hand obscuring the midorbital region and would benefit from a true orbital hypertelorism correction. C,D. This patient would benefit from nasal reconstruction alone.

  • Nasal appearance recognizing that hypertelorism may be masked by surgical augmentation of a depressed nasal dorsum

  • Other contributors to the appearance of hypertelorism should also be assessed, such as exotropia, dystopia canthorum, epicanthal folds, narrow palpebral fissures, and widely spaced eyebrows.

  • Extraocular muscle function, gross vision, presence of exorbitism, and degree of corneal protection should be noted.

  • Evaluate for soft tissue excess that may be present or be created by medialization of the orbits.

  • In assessing the need to correct hypertelorism, a technique to obscure the naso-orbital region can help determine whether the lateral orbital wall distances are abnormal and if so, would necessitate either facial bipartition or box osteotomies. If not, then medial wall osteotomies or camouflage rhinoplasty procedures would be effective (FIG 3).

  • The cranial shape and fontanelle patency should be assessed for associated craniosynostosis in cases of craniofrontonasal dysplasia and craniofacial dysostoses, which may alter surgical planning.

  • Further examination should identify other findings suggestive of an underlying syndromic diagnosis, which may influence treatment planning and timing such as midface retrusion, severe exorbitism, and indications of elevated intracranial pressure.

  • Preoperative consultations are routinely obtained from ophthalmology, neurosurgery, and anesthesia.


  • Preoperative imaging with computed tomography (CT) scans (axial, sagittal, and coronal) of the craniofacial skeleton should be obtained, preferably with a low-dose, bone-only window radiation protocol to obtain a 3D reconstruction for full visualization of the craniofacial region.

  • MRI is indicated for assessment of midline tumors and encephaloceles and to assess the hypothalamic-pituitary system in specific cases.

  • Vascular studies (CT angiogram/venogram, MR angiogram). A CT arteriogram and venogram of the head and neck, or comparable vascular study, may be indicated in select cases for the purpose of identifying cerebral venous drainage anomalies commonly found in these patients as well as the vascular pathways in cases of encephaloceles.

  • Printing of 3D surgical models from CT scans is of great benefit in surgical planning and mock surgery (FIG 4).


  • Hypertelorism does not always necessitate operative intervention.

  • A mild degree of hypertelorism is considered attractive and may not warrant extensive surgical procedures for correction.

    FIG 4 • Example of a 3-D skull model before and after mock surgery.

  • Surgical management of hypertelorism may be directed toward the nose as a camouflage procedure such as nasal dorsal augmentation and correction of epicanthal folds.


Nov 24, 2019 | Posted by in Craniofacial surgery | Comments Off on Facial Bipartition

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