A Risk Calculator for Predicting Enophthalmos following Orbital Fracture Repair

Enophthalmos is an undesired outcome of orbital fracture repair (OFR). Risk factors for postoperative enophthalmos remain unclear. The authors sought to develop and validate a risk calculator for more accurate prediction of this outcome. The authors retrospectively reviewed adult trauma patients who underwent OFR at 2 trauma centers over 8 years. Patients with postoperative follow-up of less than 2 weeks were excluded. The primary outcome of this study was incidence of postoperative enophthalmos at 2 or more weeks after OFR. The C-statistic (area under the ROC curve) and Hosmer-Lemeshow tests were used to assess the accuracy of the risk model.

Of 501 patients with OFR, 349 were included. Twenty-seven patients (7.7%) had postoperative enophthalmos. The risk model was developed and partially validated using patient data from 2015 to 2019 ( n = 253), and fully validated from 2020 to 2022 ( n = 96). Risk factors for postoperative enophthalmos were older age, preoperative enophthalmos, medial wall involvement, nearly total orbital floor defects, and delayed surgical repair beyond 1 month from injury. There was an incremental increase in the odds of postoperative enophthalmos with longer duration from injury to surgery. The authors' risk model showed very good discrimination (C-statistic, 84.5%) and calibration ( P = 0.83). It was highly accurate in predicting enophthalmos using the validation data set (C-statistic, 0.89). For a risk cutoff of 9.5%, the sensitivity and negative predictive value were 85% and 99%, respectively.

The authors designed the first validated risk calculator that can be used to rule out enophthalmos following OFR. Their risk calculator enables surgeons to preoperatively predict the absence of postoperative enophthalmos in 99% of cases.

Risk, III.