A prospective and nationwide study investigating endophthalmitis following pars plana vitrectomy: incidence and risk factors.

BACKGROUND/AIMS This is the first nationwide prospective study to investigate the incidence and risk factors of endophthalmitis following pars plana vitrectomy (PPV). METHODS This was a prospective, nationwide case-control study. Cases of presumed infectious endophthalmitis within 6 weeks of PPV were reported via the established British Ophthalmological Surveillance Unit. The surveillance period was 2 years. Controls (patients who had PPV but no endophthalmitis) were recruited from nine randomly selected UK centres. RESULTS 37 reports were received and 28 cases met the diagnostic criteria for presumed infectious endophthalmitis following PPV. The incidence of endophthalmitis following PPV was 28 cases per 48 433 PPVs (1 in 1730 with a 95% CI of 1 in 1263 to 1 in 2747). 272 controls were randomly recruited from nine UK centres. Smaller gauge port sizes were not found to be a risk. Immunosuppression (OR 19.0, p=0.001) and preoperative topical steroids (OR 131.4, p<0.001) increased the endophthalmitis risk. Operating for retinal detachment was associated with a reduced risk of endophthalmitis (OR 0.10, p=0.005). CONCLUSIONS Endophthalmitis following PPV is rare. Operating with smaller gauge port sizes does not increase the risk of endophthalmitis.