Treatment of posttraumatic ocular dysmotility using autogenous buccal fat grafts in a porcine model

Diplopia occurring after orbital trauma is a complex and difficult clinical problem. Numerous potential mechanisms exist by which it may occur. Restri ctive ocular dysmotility caused by intraorbital scarring is a major compone nt in diplopia's pathogenesis. The current large animal study was conducted to develop an experimental model of restrictive ocular dysmotility that wo uld quantitatively characterize the biomechanical properties of the globe r otations. Using this model, a novel method of restoring the low-friction mi lieu within the orbit by interposing a buccal fat graft was tested. In the initial stage, the baseline force duction was measured in 20 pig eyes using a highly sensitive, digital tensiometer. Traumatic violation of Tenon's fa scia with electrocautery into the extraconal fat and the periorbita was fol lowed by direct suturing of the extraocular muscle to the nearest orbital p eriosteum. After 6 weeks, the measurements (again in the field of the traum atized muscle) were repeated, and the eyes were divided into two treatment groups (n = 10 eyes per group). The left eye received the standard lysis of adhesion, whereas the right eye received lysis and buccal fat interpositio n grafting. The third and final force measurements were performed 6 weeks a fter treatment. The results showed a baseline linear load-displacement curv e of 0 to 8 mm, with the globe rotating 400 mu m for every 1000 mg of tensi le load. Surgical trauma increased the slope as defined by load/displacemen t but, surprisingly, the relationship remained linear in the entire range f rom 2 to 8 mm. This linear relationship was seen in all stages: baseline, a fter trauma to Tenon's fascia, after surgical lysis alone, and after lysis with buccal fat interposition. The difference was in the slope, or stiffnes s. Lysis alone partially reduced the slope, but it was still higher than ba seline. Lysis and buccal fat grafting returned the slope to near baseline. This, however, did not reach the level of statistical significance. It seem s that a focal intervention along the course of an extraocular muscle alter ed the composite behavior of orbital resistance to globe rotation. Although buccal fat grafting did not significantly improve motility, it did not wor sen it.