The effects of antiglaucoma medications on the ocular surface in unilaterally treated glaucoma patients

To investigate the cytological and inflammatory effects of topical antiglaucoma medications on the ocular surface by comparing treated and untreated eyes in unilateral glaucoma patients.

This observational, case-control study involved 69 patients with unilateral glaucoma, receiving monotherapy with prostaglandin analogues. The untreated fellow eyes served as controls. Tear break-up time (TBUT), Schirmer test, conjunctival impression cytology, and tear cytokine levels [interleukin (IL)-1β and IL-6] were assessed in both eyes. Comparisons between treated and untreated eyes, correlations among ocular surface parameters, and linear mixed-effects analyses according to treatment duration were performed.

TBUT was significantly lower in treated eyes than in untreated eyes (p < 0.001), whereas Schirmer test results did not differ significantly (p = 0.318). Conjunctival impression cytology analysis showed that goblet cell count was significantly lower (p < 0.001) and Nelson grading was higher (p < 0.001) in the treated eyes. Inflammatory cytokine analysis revealed significantly elevated levels of IL-1β and IL-6 in the treated group (p < 0.001). Goblet cell count correlated positively with TBUT, whereas both cytokines correlated negatively with goblet cell count. Linear mixed-effects analyses showed that longer treatment duration was associated with greater treated-fellow eye divergence in TBUT and IL-6, but not in the other parameters.

Long-term use of preservative-containing antiglaucoma medications is associated with goblet cell loss, conjunctival squamous metaplasia, increased ocular surface inflammation, and tear film instability, findings that are most consistent with an evaporative-type dry eye pattern. This interpretation is further supported by the concordant findings of conjunctival impression cytology and tear inflammatory cytokine analysis.