[The measurement of orbital volume in reconstruction of the orbital walls].

Before reconstruction of the orbital walls and other surgical procedures involving the orbits leading to a modification of pathologically altered orbital volumes, it is useful to measure these volumes in order to allow a more precise correction. Orbital volumetric studies on 22 patients and 6 dry skulls were performed using high resolution computer tomography. Fourteen patients presented enophthalmos of various origin, 3 patients fibrous dysplasia involving the orbits and 5 patients showed orbital pathology. In 10 patients with unilateral post-traumatic enophthalmos an increase of the bony orbital volume of 20.1% in the average was found corresponding to an enophthalmos of 3.5 mm in the average. Correlation between the severity of the enophthalmos and the increase in orbital volume was found. Enophthalmos could not be correlated to the intraorbital fat volume, especially no atrophy of orbital fat could be demonstrated in these patients. Normal orbital volume measurements of patients and dry skulls were compared to those found in the literature. Planning of the surgery was therefore facilitated before correction of enophthalmos, reconstruction of bony orbital contour after tumor-resection and in patients with fibrous dysplasia. Results suggest that the bony enlargement, followed by a change in soft-tissue shape and position is the usual cause of posttraumatic enophthalmos. Changes in volume of soft-tissues themselves are less significant.