Effect of the Preservative Benzalkonium Chloride in Prostaglandin Analogues on Corneal Sensitivity

Purpose: To investigate the effect of a prostaglandin (PG) analogue with or without preservative benzalkonium chloride (BAK) on corneal sensitivity. Methods: Central corneal sensitivity was measured prospectively with a Cochet-Bonnet esthesiometer in patients with normal tension glaucoma (NTG) or primary open angle glaucoma (POAG) before and 1 and 3 months after treatment. All patients began treatment with PG monotherapy with or without BAK preservative. Results: The study enrolled 84 patients: 52 NTG and 32 POAG. The treatment was PG with BAK preservative in 45 eyes and without BAK preservative in 39 eyes. Without BAK, the mean corneal sensitivity was 58.22 +/- 3.56, 57.77 +/- 4.59, and 56.33 +/- 5.47 mm before and after 1 and 3 months, respectively; with BAK the mean corneal sensitivity was 58.20 +/- 4.51, 56.31 +/- 6.22, and 55.52 +/- 6.23 mm. Corneal sensitivity was reduced significantly in patients using PG with the preservative BAK after 3 months (p = 0.033). Co-administration of artificial tears did not affect this reduction in corneal sensitivity. Conclusions: PG with the preservative BAK reduced corneal sensitivity and artificial tears did not improve this reduction. Reduced corneal sensitivity and accompanying side effects should be considered in the long-term use of PG with the preservative BAK.