Restricted ocular motility after orbital trauma—Studies with an animal model

Objective: Our purpose was to develop a quantitative model of restricted ocular motility (fat adherence syndrome) in the pig orbit to facilitate research into pathogenesis and treatment. Methods: Twenty eyes of 10 pigs were used in an attempt to create a fibrous adhesion between either the inferior rectus or the medial rectus muscle and the adjacent periorbita. Quantitative forced ductions were performed preoperatively and 6 weeks postoperatively with an electronic force gauge. Results: Forced ductions displayed a linear relationship to displacement over the range tested, both preoperatively and postoperatively. Although increased resistance to forced ductions was produced in 10 of the 20 (50%) eyes, the average changes were not statistically significant. The absolute change in force (Postoperative — Preoperative) was linearly related to the amount of ocular rotation. Reproducibility of measurements was markedly improved by the use of a motorized forced duction apparatus compared with manual rotation. Conclusions: The results from this study, and those from previous work, suggest that the classic fat adherence syndrome is an uncommon event, even after significant soft tissue injury in the orbit. Further studies are needed to more completely define the risk factors and pathogenesis of the fat adherence syndrome and the suitability of the pig orbit as a model.