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<b><i>Introduction:</i></b> Most intraocular pressure (IOP)-lowering eye drops are preserved with benzalkonium chloride (BAK). This can increase side effects and decrease adherence. Particularly, damage to the mucin-producing conjunctival goblet cells may be an issue due to instability of the tear film. We aimed to investigate the effect of IOP-lowering eye drops preserved with BAK on cultured human conjunctival goblet cells. <b><i>Methods:</i></b> Eye drops Brimonidine Tartrate Teva (BT) with 0.005% BAK, Dorzolamide Stada (DS) with 0.0075% BAK, Optimol^® (OP) with 0.01% BAK, and Latanoprost Teva (LT) with 0.02% BAK were included. Human primary cultured goblet cell survival was evaluated using a lactate dehydrogenase assay on human goblet cells after treatment for 30 min and 6 h with the different anti-glaucoma drug formulations. <b><i>Results:</i></b> All eye drops examined, except BT, reduced goblet cell survival. The impact of eye drops on goblet cell viability was correlated with the time of exposure as well as to the concentration of BAK. After 30 min of exposure, cell viability was 93% for BT (0.005% BAK; <i>p</i> = 0.93), 71% for DS (0.0075% BAK; <i>p</i> = 0.067), 70% for OP (0.01% BAK; <i>p</i> = 0.054), and 69% for LT (0.02% BAK; <i>p</i> = 0.022), and exposure for 6 h reduced cell survival to 74% for BT (<i>p</i> = 0.217), 52% for DS (<i>p</i> = 0.011), 34% for OP (<i>p</i> = 0.017), and 31% for LT (<i>p</i> = 0.0007). <b><i>Conclusion:</i></b> LT, OP, and DS reduced human goblet cell survival in a time-dependent manner. BT did not affect goblet cell survival. Cell survival was correlated with the BAK concentration in the eye drops making 0.02% BAK-preserved LT most toxic and 0.005% BAK-preserved BT least toxic. Based on the present study, decreasing BAK in eye drops for chronic use seems important to reduce damage to the goblet cells. However, future studies are needed to further explore this finding.

ObjectiveTo 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 analysisPrimary 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.ResultsAfter 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).ConclusionPF-LT compared with various branded and generic LT preparations containing BAK are less cytotoxic when applied to cultured GCs.

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