Quantitative analysis of conjunctival goblet cells after chronic application of topical drops

Chronic topical glaucoma therapy has been reported to cause deleterious changes to the ocular surface epithelial layers. We compare changes in the number of goblet cells after chronic exposure to latanoprost preserved with 0.02% benzalkonium chloride (BAK) eye drops (Xalatan; Pfizer, NY, USA), travoprost preserved with sofZia eye drops (Travatan Z; Alcon, Fort Worth, TX, USA), or preservative-free artificial tears (Refresh Plus; Allergan, Irvine, CA, USA).

Fifteen New Zealand white rabbits were randomised into groups of five (one eye was randomised for treatment) and received once-daily topical application of one of the three treatments for 30 days. Enucleation was performed at the end of the study followed by histologic analysis using mucin stains to identify goblet cells. Goblet cells were quantified and analysed using Student t tests to compare means between groups.

Goblet cells per high-power field were 2.21 (+/-0.40) in the latanoprost with BAK group, 6.02 (+/-1.20) in the travoprost with sofZia group, and 7.03 (+/-1.33) in the preservative-free artificial tear group. The number of goblet cells in the latanoprost with BAK group was significantly lower than the other two groups (P=0.0001). There was no statistically significant difference in goblet cell numbers between the travoprost with sofZia and preservative-free artificial tear group (P=0.24).

Our study illustrates that, in this animal model, once-daily dosing of latanoprost with 0.02% BAK resulted in goblet cell loss compared with dosing with either travoprost with sofZia or preservative-free artificial tears.