Incidence and Clinical Course of Acute Endophthalmitis after Idiopathic Epiretinal Membrane Surgery with Microincision Vitrectomy

Purpose: To investigate the incidence and clinical course of acute endophthalmitis after idiopathic epiretinal membrane (iERM) surgery employing microincision vitrectomy (MIVS). Methods: We retrospectively reviewed the medical records of eyes with acute endophthalmitis developing after iERM surgery via 23-or 25-gauge MIVS from 2011 to 2021. The incidence, culture-positive rate (and responsible bacteria), final visual acuity (VA), and factors affecting poor visual outcomes were assessed. Results: Acute endophthalmitis developed in 20 of the 12,921 eyes (0.15%) after MIVS. Of these, 14 of 3,180 eyes treated via iERM (0.44%, one per 227 procedures) developed endophthalmitis; the incidence ratio (iERM versus non-iERM) was 7.1 (p < 0.001, 95% confidence interval [CI] = 2.6-22.7). At least one sclerotomy remained unsutured in all eyes after iERM surgery. Thirteen eyes (92.9%) were given intravitreal antibiotic injections after emergency vitrectomy, and one eye was treated with in-travitreal antibiotic injection alone. Staphylococcus epidermidis was cultured from four eyes (28.6%); three strains were methi-cillin-resistant. All final VAs were not better than the initial VAs; the average VA decreased from 20/42 to 20/259 (p < 0.001). Six eyes (42.9%) attained legal blindness status (final VA < 20/200); Macular invasion was a unique risk factor for such blindness (p = 0.020, odds ratio = 35.0, 95% CI = 1.7-703.0). Conclusions: Acute endophthalmitis developing after iERM surgery with MIVS was more common than such endophthalmitis af-ter other retinal surgery. Approximately 40% of the former patients became legally blind, and the risk was higher in eyes with macular involvement of endophthalmitis. J Korean Ophthalmol Soc 2023;64(2):132-141