Author(s): Olivia J. K. Fox, Samantha Bobba, Calum W. K. Chong, Sarah B. Wang, Michael C. Wehrhahn, Simon Irvine, and Ian C. Francis
Purpose: The purpose of this study is to reassess the pathogenesis of postoperative endophthalmitis (POE), aiming to determine the presence of bacteria in the anterior chamber at the conclusion of phacoemulsification cataract surgery, and the subsequent development of POE. Methods: A single surgeon performed all cataract procedures across the two nominated day surgical centres. Phacoemulsification surgery with intraocular lens implantation (IOL) was performed on 209 eyes. Patient demographics and POE risk factors were obtained, as well as an anterior chamber (AC) aspirate from each patient at the conclusion of the surgical procedure. The aspirate was cultured for 1 – 5 days. Fourteen eyes also underwent bacterial 16S polymerase chain reaction (PCR) analysis of the AC aspirate. Any subsequent development of POE was recorded. No intracameral antibiotics were used. Results: Of the 209 cultures, three cases (1.4%) were positive for growth (95% confidence interval). The three positive cases yielded different microorganisms. One case was positive for bacteria (Corynebacterium species) while the other two cases were positive for fungi (Candida species and a Zygomycete). Cases with positive culture growth had no statistically significant difference in the incidence of preoperative, operative and postoperative risk factors for POE, compared with patients with negative culture. No patient in this study developed POE. Conclusion: The bacterial contamination rate of the AC after phacoemulsification surgery with IOL implantation is extremely low. Strict aseptic technique and definitively closed incisions can potentially be attributed to the zero percentage incidence of POE. It is probable that POE is more likely due to postoperative factors.
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