Orbital Volume Measurements Research Articles

Prediction of enophthalmos by computed tomography after 'blow out' orbital fracture.

In 11 patients with blow out fracture of the orbit, measurement of orbital volume using computed tomography (CT) more than 20 days after injury correlated well with enophthalmos measured from the same scans (r = 0.87, p < 0.001, SEE 0.63 mm), with a 1 cm3 increase in orbital volume causing 0.8 mm of enophthalmos. This confirms the cause of enophthalmos after blow out fracture to be increase in orbital volume rather than fat atrophy or fibrosis. In a further 25 patients scanned within 20 days of injury the degree of enophthalmos was less marked than would be predicted from the orbital volume measurement. This was probably because of the presence of oedema, haemorrhage, or both behind the globe which would prevent immediate development of enophthalmos. CT measurement of orbital volume within 20 days of injury may predict the final degree of enophthalmos and identify those patients at risk of late enophthalmos, allowing appropriate early surgical intervention.

Orbital volume measurement in the management of pure blowout fractures of the orbital floor.

With the recent advent of accurate orbital volume assessment by computed tomography, a retrospective analysis was made of 31 patients with 'pure' blowout fracture of the orbital floor, managed either surgically or conservatively, to determine whether orbital volume measurement could provide an additional parameter of use in the management of such fractures. There was a significant difference in orbital volume discrepancy between patients managed surgically or conservatively suggesting that this investigation may be of use in decision making on surgical intervention in patients with orbital blowout fractures.

Orbital Volume Measurements in Enophthalmos Using Three-Dimensional CT Imaging

Orbital Volume Measurements in Enophthalmos Using Three-Dimensional CT Imaging

Orbital volume measurements in enophthalmos using three-dimensional CT imaging.

The purpose of this study was to investigate enophthalmos by measuring the volume of various orbital structures using off-line computer techniques on images generated by a CT scanner. Eleven patients with enophthalmos had CT scans of the orbits consisting of 30 to 40 adjacent 1.5-mm slices. The data from the scans were analyzed on a Nova 830 stand-alone computer system using software programs that allowed measurement of total bony orbital volume, total soft-tissue volume, globe volume, orbital fat volume, neuromuscular tissue volume, and apex-to-globe distance in the horizontal plane. These data were analyzed comparing the volumes in the normal eye with the volumes in the enophthalmic eye in each patient. The analysis demonstrated a statistically significant increase in bony orbital volume in the enophthalmic eye, but the total soft-tissue volume, fat volume, neuromuscular tissue volume, and globe volume were the same as in the normal eye. The apex-to-globe distance, a measure of the degree of enophthalmos, was less in the enophthalmic eye than in the normal eye. These results suggest that in the majority of patients, the cause of posttraumatic enophthalmos is increased bony orbital volume rather than by soft-tissue loss or fat necrosis. (Several patients showed no volume discrepancies, and it is likely that cicatricial contracture is responsible for the enophthalmos in these cases.) This study suggests that the objective of surgery for correction of enophthalmos in patients with a volume discrepancy should be to decrease the volume of the bony orbit and to increase the anterior projection of the globe.