CT ASSESSMENT OF ORBITAL VOLUME IN LATE POSTTRAUMATIC ENOPHTHALMOS

The potential of CT to facilitate preoperative planning of reconstruct ive maxillofacial surgery by orbital volume quantification was analyse d in II patients with traumatic enophthalmos as a late sequela of zygo matic fractures. We carried out biplanar CT examination of the orbits, and calculated total orbital and fat volumes for the healthy and enop hthalmic sides. Displacement of the orbital floor and lateral wall was present in 11 and 7 cases respectively. Indentation of the medial wal l was noted in 9 cases. Quantitative evaluation of the orbital cavity revealed a significant in crease (P < 0.0188) ill total volume on the enophthalmic side, the difference between the two sides ranging from 9 .2 % to 36.4 %, mean 17.9 %. The degree of enophthal mos, measured rad iologically as 2.5-5 mm, correlated with the increase in orbital cavit y volume (P = 0.000076). Enophthalmos was 2.5-3 mm in 7 cases (63.6 %) and 3.5-5 mm in 4 (36.4 %). This corresponded with a mean increase in orbital volume of 3.4 mi (12.3 %) and 7.1 ml (27.8 %) respectively. F at atrophy was not an aetiological factor in the production of post-tr aumatic enophthalmos.