Abstract. This article presents observations of ocular surface clinical condition in patients with primary open-angle glaucoma who had been receiving antihypertensive drugs containing preservatives over an extended period. The study comprises a total of 74 eyes, with patients categorized into three groups. The initial group consists of individuals who had been on a long-term regimen (up to 18 years) of antihypertensive medication containing benzalkonium as a preservative. The second group encompasses 12 patients (24 eyes) who were administered prostaglandin drugs via disposable dropper tubes, devoid of preservatives. The treatment duration for this group ranged from 2 to 2.5 years. Lastly, the third group comprised individuals exhibiting symptoms of conjunctivitis, chosen for the diagnosis of dry eye syndrome based on their subjective complaints. This group includes 10 patients, totaling 20 eyes. Upon analysis, approximately 40% of patients in the main group exhibited symptoms indicative of dry eyes. In the control group that received the preservative-free drug, the occurrence of dry eye symptoms was notably lower at 16.6%, while in the other control group, this frequency stood at approximately 30%. Consequently, the group consistently receiving drugs with a preservative showed a slightly higher percentage in the detection of dry eye