Abstract： AIM:To investigate the effect of unilateral endoscopic dacryocystorhinostomy on binocular surface indexes.METHODS:Totally 45 cases with monocular primary acquired nasolacrimal duct obstruction(PANDO)who successfully underwent endoscopic dacryocystorhinostomy between 1 December 2022 and 31 July 2023 were enrolled in the study.Ocular surface indexes,including the non-invasive tear break-up time(NIBUT),Sj?gren's International Collaborative Clinical Alliance ocular staining score(SICCA OSS),Korb score of lid wiper and Schirmer test scores,were collected preoperatively and at 0.5,1 and 3 mo post-operatively.Subsequently,various indexes were compared at each time point between the operated and healthy eyes pre-and post-operatively.RESULTS:There was no significant differences between operated and healthy eyes in NIBUT,SICCA OSS,Korb scoresand Schirmer test(all P＞0.05).Furthermore,the Korb scores of operated eye at 0.5,1 and 3 mo post-operatively were significantly lower than the preoperative value(P=0.034,0.044,0.027).Moreover,the Schirmer test score of the operated eye at 1 mo post-operatively was significantly lower than the preoperative value(P=0.0461).CONCLUSION:After a successful endoscopic dacryocystorhinostomy,tear drainage is restored,however,ocular surface damage worsens.These changes typically peak at 1 mo post-operatively before gradually improving.