Orbital Soft Tissue Volume Research Articles

The effect of buphthalmos on orbital growth in early childhood: Increased orbital soft tissue volume strongly correlates with increased orbital volume

Purpose: Our purpose was to evaluate the effect of increased orbital soft tissue volume on orbital growth. Method: Patients with unilateral or significantly asymmetric bilateral buphthalmos as determined by axial computed tomography scan were recruited. Volumetric determinations of the bony orbit with use of axial 1.5 mm sections on computed tomography were undertaken. Statistical analysis of the paired ocular length measurement and bony orbital volume measurements for each patient were performed. Results: Eight patients (mean age 41 months) with a 15% or greater difference in axial length were enrolled. The mean axial length of the buphthalmic globes was 23% greater than that of the contralateral globes. Orbits harboring a buphthalmic globe had an orbital volume 11% greater than on the contralateral side. Conclusion: Increased orbital soft tissue volume as evidenced by buphthalmos was significantly associated with enlarged bony orbital volume. This indicates that soft tissue volume is a determinant of orbital volume and suggests that orbital tissue expanders might enhance bony development in patients with anophthalmos or microphthalmos and after early enucleation.

Mechanisms of Global Support and Posttraumatic Enophthalmos

The mechanisms of posttraumatic enophthalmos were evaluated to determine the interrelation between fat and ligaments in globe support. Anatomic studies demonstrate that the ligaments form an essential "sling" framework for the globe but are alone insufficient to maintain the globe's full forward position. Removal of extramuscular fat in cadavers and in patients undergoing blepharoplasty did not significantly change globe position. Loss of intramuscular cone fat (atrophy or displacement) in cadavers and patients produced enophthalmos. Fat atrophy is not a prominent feature in most patients with posttraumatic enophthalmos. Some loss of intramuscular cone fat from displacement outside the muscle cone is frequently present. The principal mechanism, however, of posttraumatic enophthalmos involves a displacement and change in the shape of orbital soft tissue. Loss of bone and ligament support permits posterior displacement and a reshaping of orbital soft tissue under the influence of gravity and the remodeling forces of fibrous scar contracture. The shape of the retrobulbar orbital contents changes from a modified cone to a sphere, and the globe sinks backward and downward. Given that the volume of orbital soft tissue is constant following trauma, procedures to restore the shape and position of the orbital soft tissue by mobilization and bone reconstruction will correct or significantly improve enophthalmos.