Augmentation of intraorbital volume with fat injection

Enophthalmos is a challenging surgical problem to correct. Standard techniques to adjust orbital volume require invasive maneuvers such as osteotomies. Fat injection may provide a simple and less-invasive way of augmenting orbital volume to correct enophthalmos.

The right eye orbital volume of 10 New Zealand White rabbits was augmented with fat. Autologous fat was diced and injected into the retrobulbar space. Computed tomographic scans were evaluated for changes in globe position and retrobulbar volume. Visually evoked potentials were conducted to test the integrity of the optic tract. Rabbits were killed at 12 weeks after surgery. Orbital exenterations were performed to allow for gross and histologic evaluation.

Right globe position showed a mean increase in eye proptosis of 3.4 mm at postoperative day 1 and 0.9 mm at 11 weeks postoperatively in comparison with the left globe position. No significant change was noted in the left globe position. Retrobulbar volume demonstrated an initial mean increase of 31 percent and a final mean increase of 9.8 percent at 11 weeks in the right eye compared with the left eye. Visually evoked potentials revealed intact optic pathways in all animals. Gross anatomical evaluation showed deposition of fat grafts. Histologic analysis showed both revascularized and necrotic areas of fat. No retinal or optic nerve damage was identified.

Fat injection can augment orbital volume in an animal model and preserve visual function. Further investigation is necessary to document the clinical safety and value of this technique in humans.