LAUSR

PURPOSE Orbital floor fracture defect size (DS) and Inferior Rectus (IR) Rounding Index are currently accepted indications for surgery to prevent late enophthalmos. Herein, we analyze the positive predictive value (PPV) of these indications. METHOD 28 patients with orbital floor fractures presenting without enophthalmos underwent Hertel exophthalmometry at presentation and at weeks 1, 2, 3, 6, 13, 26, and ≥52 following injury. Orbital defect size (DS) and IR Rounding Index (IR) were measured from CT scans, and PPVs of defect size ≥1.5-2cm 2 and IR Rounding Index ≥1 for enophthalmos (≥2mm) were calculated. RESULTS 19 patients had isolated orbital floor fractures (Group A), 3 had non-continuous orbital floor and medial wall fractures (Group B), and 6 had continuous orbital floor with medial wall fractures (Group C). Mean follow-up time was 440 days. Of all patients, 20 had DS ≥1.5cm 2, 12 had DS ≥2.0cm 2, and 13 had IR Rounding Index ≥1. Of the 28 patients, only one from group A and two from group C developed enophthalmos of 2mm only. The PPV of orbital floor DS ≥1.5cm 2 and ≥2cm 2 (groups A and B only) for late enophthalmos was 6.7% and 0%, respectively. The PPV of IR Rounding Index ≥1 for late enophthalmos (all groups) was 0%. CONCLUSIONS For patients with orbital floor fractures presenting without enophthalmos, defect size ≥1.5cm 2 and ≥2cm 2 , and IR rounding ≥1 are weakly predictive of late enophthalmos. Furthermore, patients who do not develop enophthalmos within 3 weeks of injury are unlikely to develop significant (>2mm) late enophthalmos.