Altered ocular surface microbiome in nasolacrimal duct obstruction: Clinical implications for intraocular surgery.

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.