Bulbar Conjunctival Changes in Primary Open-Angle Glaucoma under Preservative-Free versus Preserved Latanoprost 0.005%

Abstract

Background: Long-term topical antiglaucoma therapy is frequently associated with alterations of the ocular surface, particularly in formulations containing preservatives such as benzalkonium chloride (BAС). Chronic exposure to preservatives may induce epithelial toxicity, destabilization of the tear film, and subclinical inflammation, ultimately contributing to the development of dry eye disease. Structural and cytological changes of the bulbar conjunctiva are considered important indicators of ocular surface impairment in patients receiving prolonged treatment.

Aim: To evaluate the condition of the bulbar conjunctiva in patients with primary open-angle glaucoma (POAG) treated with latanoprost 0.005% eye drops with and without preservatives .

Methods: A total of 36 patients with POAG were enrolled and divided into two groups. Study group 1 included 21 patients (21 eyes) receiving preserved latanoprost 0.005% containing BAC. Study group 2 -15 patients (15 eyes) treated with preservative-free latanoprost 0.005% (Protriaxin matrix). A control group consisted of 21 healthy participants. All subjects underwent ophthalmological examination, including evaluation of the ocular surface and cytological assessment of the bulbar conjunctiva. Impression cytology was used to analyze epithelial cell morphology and the presence of inflammatory cells. Statistical analysis included calculation of odds ratios (OR) and confidence intervals (CI).

Results: No significant differences were observed in the overall cytological architecture of the bulbar conjunctiva between groups receiving preserved and preservative-free therapy. However, inflammatory cell infiltration was detected significantly more frequently in patients treated with preserved latanoprost (42.8%) compared to those receiving preservative-free formulation (6.6%) (p = 0.0279). Patients using preserved latanoprost demonstrated a 10.5-fold increased likelihood of inflammatory cell presence compared to the preservative-free group (OR = 10.5; 95% CI [1.15–95.25], p = 0.0366). These findings suggest the presence of subclinical inflammation associated with preservative exposure, even in the absence of overt cytological alterations.

Conclusions: These findings support the preferential use of preservative-free antiglaucoma eye drops, particularly in patients with pre-existing or suspected ocular surface damage, to minimize cytological changes and subclinical inflammation during long-term therapy.