Endophthalmitis after Pars Plana Vitrectomy A 20- and 25-Gauge Comparison Allen Y. H. Hu, MD, 1 Jean-Louis Bourges, MD, 1,2 Sumit P. Shah, MD, 1 Anurag Gupta, MD, 1 Christine R. Gonzales, MD, 1 Scott C. N. Oliver, MD, 1 Steven D. Schwartz, MD 1 Objective: Recent retrospective analyses have suggested that postoperative endophthalmitis may be more frequent with 25- than 20-gauge pars plana vitrectomy (PPV). Because the infection risk may depend on the suturing status of the sclerotomy, and the perioperative anti-infection protocol, we compared the incidence rate of endophthalmitis after sutureless 25-gauge versus sutured 20-gauge PPV on a large cohort of patients operated with a standardized perioperative anti-infection protocol. Design: Retrospective comparative case series. Participants: Consecutive patients who underwent 20- or 25-gauge PPVs at a single center over a multi- year period. Methods: We analyzed 3597 consecutive PPVs. Patients with a pre-PPV diagnosis of endophthalmitis, PPVs performed for implantation of drug delivery devices, or 25-gauge PPVs with all sclerotomies sutured closed were excluded. Patients with 1 week of follow-up were divided into 2 study groups by sclerotomy status at the end of surgery: the 20-gauge group had 3 sutured 20-gauge sclerotomies, and the 25-gauge group had 1 unsutured 25-gauge sclerotomy. Endophthalmitis was defined by clinical criteria independent of microbiological results. Main Outcome Measures: The incidence of endophthalmitis was compared between 25- versus 20-gauge groups. Results: Of 3372 PPV surgeries meeting inclusion and exclusion criteria, 1948 and 1424 surgeries were 20- and 25-gauge PPVs, respectively. Average age ( standard deviation) of patients was 54.6 ( 22.6) and 64.4 ( 16.5) years in the 20- and 25-gauge PPV groups, respectively (P0.0001). Median post-PPV follow-up time was not significantly different between the 2 groups (12.5 vs 13.0 months; P = 0.69). Endophthalmitis was observed in 1 patient (0.07%; 95% confidence interval, 0%– 0.21%) from the 25-gauge group and none in the 20-gauge group (P = 0.42; Fisher exact test, 2-tailed). The use of air/gas endotamponade (P0.0001) and intravitreal triamcinolone (P0.001) was more common in 25- versus 20-gauge PPV. Conclusions: The incidence of endophthalmitis was low in both groups. We were unable to show a significant difference in the incidence of endophthalmitis between sutureless 25-gauge and sutured 20-gauge PPV, and conclude that a careful perioperative anti-infection protocol may reduce 25-gauge PPV endophthalmi- tis risk to that of 20-gauge PPV. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2009;116:1360 –1365 © 2009 by the American Academy of Ophthalmology. Rates of endophthalmitis after conventional pars plana vit- rectomy (PPV) have decreased over the past 20 years. Ho and Tolentino 1 reported an endophthalmitis rate as high as 0.15% after PPV in 1984. In subsequent years, rates re- ported from the mid-1980s to early 2000s have decreased, ranging from 0.03% to 0.05%. 2–6 Recent advances in retinal surgery techniques and instru- mentation, such as 25-gauge PPV, have permitted use of sutureless vitrectomy through small, self-sealing, transcon- junctival wounds, which allow patients to recover more quickly and comfortably. These and other perceived advan- tages have led surgeons to expand the indications for and increase use of 25-gauge sutureless PPV. 7–13 Despite these advantages, concerns have been raised about the lack of high-level clinical trials based evidence demonstrating safety and efficacy. 14 Postoperative endoph- thalmitis after 25-gauge vitrectomy was first reported in 2005, followed by other reports in 2006 through 2008. 15–19 Some studies have suggested that the postoperative endoph- thalmitis rate is higher with 25- than 20-gauge PPV. In a single-center comparison of 20-gauge sutured vitrectomy versus 25-gauge sutureless vitrectomy, Kunimoto et al 16 reported a 12-fold higher incidence of endophthalmitis with 25- versus 20-gauge surgery. More recently, in a study of pooled data from multiple surgeons at 7 centers, Scott et al 17 reported a 28-fold higher rate of endophthalmitis with 25- versus 20-gauge. Proposed hypotheses explaining why sutureless transcon- junctival 25-gauge PPV may lead to a higher rate of postop- erative endophthalmitis vary. Some theories relate to a lack of complete wound closure. 20 Unsutured wounds may lead to early postoperative hypotony in 0% to 30% of 25-gauge cases, allowing an intraocular influx of extraocular fluid and micro- organisms. 8,10 –13,21 (Gupta et al IOVS 2003, v 44). Others 1360 © 2009 by the American Academy of Ophthalmology ISSN 0161-6420/09/$–see front matter Published by Elsevier Inc. doi:10.1016/j.ophtha.2009.01.045