Endophthalmitis after 25-gauge and 20-gauge pars plana vitrectomy: incidence and outcomes

Purpose: To compare the rates of endophthalmitis after 20-gauge versus 25-gauge pars plana vitrectomy (PPV) and to investigate clinical features of, and visual acuity outcomes, for patients with endophthalmitis after PPV.

Methods: A computerized database search was performed at each author's institution to identify all patients who underwent PPV by any of the authors between January 1, 2005, and December 31, 2006, and were subsequently treated for endophthalmitis. In addition, all patients who underwent PPV and were subsequently treated for endophthalmitis at Pennsylvania State College of Medicine (Hershey, PA) and Bascom Palmer Eye Institute (Miami, FL) during the study period were included. The medical records of these patients were reviewed to confirm that the endophthalmitis was associated with PPV and to collect clinical data to meet the study objectives.

Results: The incidence of endophthalmitis during the study period was 2 cases per 6,375 patients (or 1 case per 3,188 patients; 0.03%) for 20-gauge PPV compared with 11 cases per 1,307 patients (or 1 case per 119 patients; 0.84%) for 25-gauge PPV (P < 0.0001). Of 11 eyes that developed endophthalmitis after 25-gauge PPV, 9 received endophthalmitis prophylaxis with subconjunctival cefazolin after surgery. Median intraocular pressure on postoperative day 1 was 13 mmHg (range, 5-27 mmHg). Median time between PPV and endophthalmitis presentation was 3 days (range, 1-15 days). Presenting vision was hand motions or better in all eyes. Initial treatment included vitreous tap and injection of antibiotics in nine eyes and PPV and injection of antibiotics in two. All patients received intraocular treatment with vancomycin, and 10 received ceftazidime treatment. Eight patients had final visual acuity of >/=20/400, and four had visual acuity of >/=20/63. Cultures were negative in three cases; no culture specimens were obtained in one case. Six of the seven isolates were coagulase-negative staphylococci, and one was enterococcus. Five of six isolates tested for sensitivity to vancomycin were sensitive, and both isolates tested for sensitivity to ceftazidime were sensitive.

Conclusions: The rate of endophthalmitis after 25-gauge PPV was significantly higher than that after 20-gauge PPV. Endophthalmitis after 25-gauge PPV occurred within 15 days of PPV, was usually due to coagulase-negative staphylococci sensitive to vancomycin, and was associated with variable visual outcomes.