PREDICTION OF ENOPHTHALMOS BY COMPUTED-TOMOGRAPHY AFTER BLOW-OUT ORBITAL FRACTURE

In 11 patients with blow out fracture of the orbit, measurement of orb ital volume using computed tomography (CT) more than 20 days after inj ury correlated well with enophthalmos measured from the same scans (r= 0.87, p<0.001, SEE 0.63 mm), with a 1 cm(3) increase in orbital volume causing 0.8 mm of enophthalmos. This confirms the cause of enophthalm os after blow out fracture to be increase in orbital volume rather tha n fat atrophy or fibrosis. In a further 25 patients scanned within 20 days of injury the degree of enophthalmos was less marked than would b e predicted from the orbital volume measurement. This was probably bec ause of the presence of oedema, haemorrhage, or both behind the globe which would prevent immediate development of enophthalmos. CT measurem ent of orbital volume within 20 days of injury may predict the final d egree of enophthalmos and identify those patients at risk of late enop hthalmos, allowing appropriate early surgical intervention.