Incidence of Endophthalmitis after 20- and 25-Gauge Vitrectomy: Causes and Prevention

Abstract

To compare endophthalmitis incidence after inpatient 20-gauge (20-G) and 25-G vitrectomies, and to examine the causes and prevention of postvitrectomy endophthalmitis.Retrospective, interventional, comparative cohort study.Six thousand nine hundred thirty-five consecutive patients undergoing pars plana vitrectomy.We compared the incidence of endophthalmitis in 3592 consecutive eyes that underwent 20-G vitrectomy between January 2000 and September 2004, and 3343 consecutive eyes that underwent 25-G vitrectomy between April 2004 and December 2007. For 25-G vitrectomy, 542 eyes with sclerotomies produced by straight incision and 2801 eyes with angled incisions were also compared. From 85 eyes that underwent 20-G vitrectomy and 128 eyes that underwent 25-G vitrectomy, ocular surface irrigation fluid and vitreous samples were collected at the end of surgery for bacterial culture.Incidence of postvitrectomy endophthalmitis.The incidence of postoperative endophthalmitis was 0.0278% (1 of 3592 eyes) for 20-G vitrectomies and 0.0299% (1 of 3343 eyes) for 25-G vitrectomies, with no significant difference. Two eyes developed endophthalmitis after vitrectomy, and visual acuity deteriorated to no light perception despite emergency vitreous surgery. The causative bacteria were methicillin-resistant Staphylococcus aureus and Enterococcus faecali; both were resistant to postoperative antibiotics. In 25-G vitrectomy, the endophthalmitis incidence was 0.18% (1/542 eyes) for straight incision versus 0% (0/2801 eyes) for angled incision, with no significant difference (P = 0.1621). Bacterial contamination rates in ocular surface irrigation fluid and the vitreous were 5.9% (5/85 eyes) and 1.2% (1/85 eyes), respectively, in 20-G vitrectomies, and 5.5% (7/128 eyes) and 2.3% (3/128 eyes) in 25-G vitrectomies, with no significant difference.The incidence of endophthalmitis was 0.03% for both 20-G and 25-G vitrectomies. This is the first data set to demonstrate no statistically significant difference between endophthalmitis rates in 20-G and 25-G vitrectomy. At the completion of 25-G vitrectomy, the ocular surface irrigation fluid and vitreous were, on rare occasion, contaminated by antibiotic-resistant bacteria. In 25-G vitrectomy, conjunctival irrigation, ensuring sclerotomy closure, and excision of peripheral vitreous may contribute to the prevention of postvitrectomy endophthalmitis.The authors have no proprietary or commercial interest in any materials discussed in this article.