Fat adherence syndrome: an animal model.

BACKGROUND

Fat adherence syndrome (FAS) is a permanent restrictive strabismus that can occur after periocular surgery or trauma. The pathophysiology is poorly characterized.

METHODS

Under varying conditions, fat autografts were secured with dissolvable sutures between the inferior rectus and the periosteum of the inferior orbital rim in both eyes of 15 New Zealand white rabbits. Sutures without fat autografts were placed in both eyes of three control rabbits. The force required to move the eyeball superiorly 4, 6, or 8 mm was measured with a digital strain gauge preoperatively and 6 weeks after surgery. Twelve of the 15 rabbits with autografts were then sacrificed, and exenteration specimens were taken. The three remaining rabbits (six eyes) were observed for 6 months after placement of fat autografts.

RESULTS

Analysis of variance allowed rejection of the null hypothesis that there was no difference among the postsurgical groups for all deflection points when 6 weeks postoperative was compared to baseline (preoperative) measurements (P < or = 0.05). Regression analyses showed that stiffness at each deflection was dependent on the amount of fat placed in the orbit. In three rabbits observed for 6 months, restriction tended to be stable over the 6-month observation period and was not alleviated by lysis of adhesions or removal of the fat grafts.

CONCLUSION

A fat autograft introduced into an extraocular wound in rabbits will produce a permanent restrictive strabismus. This model may prove useful in the study of FAS.