Magnetic Intraocular Foreign Body Injuries: Intravitreal Antibiotic Prophylaxis, Endophthalmitis Risk and Prognostic Factors

Purpose: To investigate the preventive effect of intravitreal injection on posterior segment magnetic intraocular foreign body (IOFB)-related endophthalmitis, the risk factors for endophthalmitis, and the prognostic factors of posterior segment magnetic IOFBs. Methods: Retrospective analysis of patients with posterior segment magnetic IOFBs admitted to Hebei Eye Hospital (2014-2022). Among them, 172 patients (2016-2022) received intravitreal antibiotics at the time of primary repair. Rates of endophthalmitis in this cohort were compared with those in a previous cohort admitted between 2014 and 2016(56 patients). In the previous cohort, patients received only primary repair. Results: The cohort was predominantly male (94%), median age 39 years. the right eye was affected in 105 patients (45%). The incidence of endophthalmitis was 4.7% (8/172) and 13.6 % (8/59) in the recent and previous cohorts, respectively, with significant difference(P=0.043). Lens capsule rupture and IOFB > 2 mm were risk factors for magnetic IOFB-related endophthalmitis (P=0.024 and P=0.031, respectively). Lens capsule rupture (OR=2.872, 95% CI 1.487-5.548, P=0.002); vitreous hemorrhage(OR=2.010, 95%CI 1.064-3.796, P=0.031); retinal detachment (OR=3.745, 95%CI 1.758-7.979, P2mm(OR=1.914, 95%CI 1.025-3.574, P=0.042) were predictors of poor visual outcome. Conclusions: Prophylactic intravitreal antibiotics can reduce the incidence of endophthalmitis in posterior segment magnetic IOFB injuries. Lens capsular rupture and IOFB > 2 mm are risk factors for endophthalmitis. In addition, lens capsular rupture, vitreous hemorrhage, retinal detachment, choroidal detachment, and IOFB > 2 mm are associated with a poor prognosis. A good initial VA is associated with a good prognosis.