Risk Factors for Endophthalmitis after Pars Plana Vitrectomies in a Tertiary Eye Institute in India

Purpose: To identify the risk factors associated with endophthalmitis after pars plana vitrectomy (PPV). Design: Retrospective case-control study. Participants: All eyes that presented with endophthalmitis after PPV within 6 weeks in a tertiary eye care center were evaluated. There were 36 cases with endophthalmitis and 93 controls without endophthalmitis. Methods: Other patients undergoing operation by the same surgeon on the same date and in the same operating room were included as controls. Univariate and multivariate regression analyses were performed to evaluate the risk factors. Main Outcome Measures: Incidence and risk factors for endophthalmitis after PPV. Results: In this study, 36 cases and 93 controls met the inclusion criteria. For endophthalmitis, 3 independent risk factors were identified: systemic immunosuppression (odds ratio [OR], 10.673; 95% confidence interval [CI], 1.114–102.292; P = 0.04), balanced salt solution (BSS) or Ringer's lactate (RL) as vitreous substitute (OR, 5.288; 95% CI, 1.769–15.813; P = 0.003), and surgery performed in the second half of the day (OR, 0.016; 95% CI, 1.266–10.398; P = 0.016). Operating on phakic patients compared with pseudophakic or aphakic patients (OR, 0.962; 95% CI, 5.049–57.644; P < 0.001) and the use of endotamponade (OR, 5.288; 95% CI, 1.769–15.813; P = 0.003) were associated with a reduced risk for endophthalmitis. In culture-positive endophthalmitis, the presence of diabetes (OR, 4.61; 95% CI, 1.15–18.39; P = 0.03), vitreous substitute (BSS or RL) (OR, 6.08, 95% CI, 1.47–25.10, P = 0.012), and pseudophakia (OR, 5.68; 95% CI, 1.37–23.47; P = 0.016) were significant risk factors. Conclusions: Patients who are immunocompromised, pseudophakic, or aphakic are at a higher risk of endophthalmitis after PPV. Endotamponade significantly mitigates the risk of infection after vitrectomy surgery.