Objective: To investigate the short-term impact on human conjunctival goblet cell (GC) survival and mucin release of acute exposure to benzalkonium chloride (BAK) preserved and preservative-free (PF) 0.005% (w/v) latanoprost (LT) eye drops, and to compare the eye drops' physicochemical properties.
Methods and analysis: Primary GC cultures were established from human conjunctival donor tissue. The impact of eye drops on GC survival was assessed using a lactate dehydrogenase assay. Mucin release was evaluated through mucin-specific immunostaining. pH value, osmolality, drop mass and surface tension for all LT eye drops were measured.
Results: After application with PF-LT for 30 min (min), the GC survival was maintained compared with control (p=0.9941), while all BAK-LT eye drops reduced survival with approximately 30% (p<0.02). Following application with PF-LT for 30 min, mucin was found around the GC nucleus, as seen in the vehicle control, indicating no secretion. In contrast, BAK-LT caused diffuse staining of mucin, similar to the secretagogue histamine, indicating stimulation of secretion. The pH value of the BAK-LT and PF-LT eye drops were 6.0-6.9 and 6.8, respectively. The osmolality was 258-288 mOsm/kg for the BAK-LT eye drops and 276 for PF-LT eye drops. The mean drop mass was 26-31 mg for the BAK-LT eye drops and 30 mg for PF-LT. The surface tension was lower for all BAK-LT eye drops (31.1-32.1 mN/m) compared with PF-LT (42 mN/m).
Conclusion: PF-LT compared with various branded and generic LT preparations containing BAK are less cytotoxic when applied to cultured GCs.
Keywords: drugs; experimental & laboratory; glaucoma; ocular surface.
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