Optimally, syringe-filling technique may reduce the risk of post-injection endophthalmitis (PIE), yet there is wide variation between ophthalmologists and jurisdictions regarding syringe-filling practices. This frequentist network meta-analysis (PROSPERO: CRD42024555196) of rare events sought to compare the odds of PIE between manufactured prefilled syringes (PFS), compounded syringes, and traditional vial preparation of syringes (VPS) for intravitreal anti-vascular endothelial growth factor therapy. Given outcome rarity, we included studies whose primary outcome was PIE incidence. From 20 observational studies (3,746 PIE events; 41,611,960 injections), the odds of PIE were significantly lower with PFS (OR: 0.45, 95% confidence interval [CI]: 0.40-0.49) and compounded syringes (OR: 0.69, 95% CI: 0.64-0.74) compared to VPS. The odds of PIE were significantly lower with PFS compared to compounded syringes (OR: 0.65, 95% CI: 0.58-0.72). The odds of culture-positive PIE were significantly lower with PFS than both VPS (OR: 0.15, 95% CI: 0.06-0.41) and compounded syringes (OR: 0.15, 95% CI: 0.05-0.44). No significant difference in culture-positive PIE was observed between VPS and compounded syringes (OR: 1.02, 95% CI: 0.66-1.58). Low certainty evidence supports that PFS significantly reduce the rate of clinical and culture-positive PIE compared to VPS and compounded syringes. Future studies should further characterize the role of confounding.
Nasolacrimal duct obstruction (NLDO) significantly alters the ocular surface microbiome, increasing bacterial load, polymicrobial colonization, and the presence of drug-resistant organisms. This microbial shift poses a serious risk for postoperative endophthalmitis following intraocular surgery. Patients with NLDO have up to a 100% conjunctival culture positivity rate, compared to 40% in normal eyes, with increased prevalence of pathogenic species such as Pseudomonas aeruginosa and Streptococcus pneumoniae. Preoperative screening using the Regurgitation on Pressure over the Lacrimal Sac (ROPLAS) test is recommended for all patients undergoing intraocular surgery; however, its low sensitivity necessitates selective use of lacrimal irrigation in high-risk individuals. Definitive management with dacryocystorhinostomy (DCR) reduces microbial burden, with normalization of flora typically occurring around 4 weeks postoperatively. In cases where DCR cannot be performed, alternative strategies such as topical/systemic antibiotics or dacryocystectomy may help mitigate infection risk. Even after successful DCR, ocular surface microbiome may resemble nasal microbiota, requiring continued vigilance during the perioperative period. These findings highlight the importance of identifying and managing NLDO before intraocular procedures to reduce the risk of vision-threatening complications.

