Reduction of microvilli could signal early damage during chronic glaucoma therapy

This retrospective study found that a decrease in conjunctival microvilli may be an early indicator of cell damage in eyes undergoing glaucoma therapy with preservative-containing formulas.

Subjects were 20 patients (40 eyes) undergoing glaucoma therapy with medications containing benzalkonium chloride and without ocular surface disorders. An age- and gender-matched group without glaucoma served as the control group. Conjunctival epithelium was evaluated with the ferning test, impression cytology with light optic microscopy, and impression cytology with scanning electron microscopy.

The mean duration of glaucoma therapy was 25.5 ± 13.8 months (range, 6 to 48 months). Treatment duration was not significantly correlated with ferning test/impression cytology grade (P = 0.1), although it was significantly correlated with microvilli count (P = 0.01). The mean ferning test, impression cytology with light optic microscopy and impression cytology with scanning electron microscopy grades were significantly lower in the control group than in the treated group.

The authors note that this study is limited by its retrospective nature and the lack of a study arm examining the effect of preservative-free glaucoma therapy on microvilli count.

However, they found that their results are in line with previous findings and indicate that preservative-free glaucoma therapies could be safer for the ocular surface than preservative-containing formulations.

They plan to conduct a prospective study with conjunctival examination at baseline and after preservative-free glaucoma therapy, thereby excluding the inflammatory effects of benzalkonium chloride.