Orbital Hypertelorism: I. Successive Surgical Attempts. Material and Methods. Causes and Mechanisms

Abstract

Orbital hypertelorism (OR.H.) is a congenitally abnormal wide distance between the orbits and hence the eyes. Trauma may produce telecanthus by displacement of part of the orbital frames; it can never produce true hypertelorism. OR.H. is not an autonomous primitive malformation but is always a secondary syndrome, generally due to a facial or cranial cleft and sometimes to craniostenosis. Interorbital distance (I.O.D.) has to be measured on the skull or, less accurately, by measuring the distance between medial canthi (I.C.D). The interpupillary distance (I.P.D.) may not give a true indication of OR.H. owing to abnormal rotation of the eyes. Average normal I.O.D. is 25 mm in females, 28 mm in males.

Classification is based on the degree of inter-orbital widening and on the general shape of the face and of the anterior cranial base. 1st degree, I.O.D. 30 to 34 mm, is euryopia or telecanthus. 2nd degree, I.O.D. more than 34 mm; orientation and shape of the orbits still are nearly normal. 3rd degree, I.O.D. usually 40 mm. Orbits appear lateralised, the cribriform plate is often prolapsed, and the distance between the lateral canthus and auditory meatus is shortened.

Working hypothesis: the distance between the optic canals is either normal or not in proportion to the increased distance between the lacrimal crest or between “useful orbits”, i.e. at the level of the equator of the eye-balls. This has been verified by radiographs and further by surgery. It should therefore be possible to displace the “useful orbits” in a transverse direction and hence to move the eyes towards each other without compressing the optic or the oculomotor nerves.

This paper describes the cranial and facial malformations observed clinically or surgically in 123 patients, 40 of whom were operated on via the cranial route, and 11 via the infrabasal (inter craniofacial) route.

A study is then made of the following determination and classification of OR.H.; hypertelorising malformations (encephaloceles, facial clefts, craniostenosis); the supposed mechanisms of OR.H.; preliminary examinations; surgical deductions drawn from malformations observed; and general indications for the cranial or extracranial route.

Ocular distance and divergence can be fairly corrected without help to binocular vision. Until to now the treatment of OR.H. has remained more morphological than functional.

When applied to OR.H., i.e. to transverse congenital craniofacial deformities, the operation to be described is part of a system of procedures focused on and around the orbit. We now have the proof that we can safely displace the whole of the “useful orbit” (i.e. within 8 to 10 mm from its apex), in the three directions: transversely, as in OR.H.; sagittally, as in retrusions of the face or frontal bone related to craniosynostosis and faciostenosis; vertically, as in orbital malpositions secondary to trauma or to some complete orbitofacial clefts, generally unilateral.