Study finds, Benzalkonium chloride increased Oxidative stres
Long-term use of topical, especially benzalkonium chloride (BAC)-preserved, antiglaucoma medications can cause a negative impact on the ocular surface. The aim of the study was to assess the effect of topical carbonic anhydrase inhibitors (CAIs) on selected oxidative stress biomarkers in the tear film.

The patients were divided into four sex-matched groups:
-group C (n=25) – control group – subjects who did not use topical antiglaucoma medications,
-group DL (n=14) – patients using preservative-free dorzolamide,
-group DL+BAC (n=16) – patients using topical BAC-preserved dorzolamide,
-group BL+BAC (n=17) – patients using BAC-preserved brinzolamide.

Subjects in all the study groups have been using the eye drops two times daily for 6–12 months.

--The advanced oxidation protein products content, Total Oxidant Status as well as superoxide dismutase and catalase activities in the group DL+BAC and BL+BAC were higher in comparison with the group C.

--The total sulfhydryl groups content was lower in the group DL+BAC and BL+BAC when compared to group C.

--Oxidative Stress Index was higher in the groups DL+BAC and BL+BAC in comparison with the groups DL and C.

Finally, topical carbonic anhydrase inhibitors maintained with benzalkonium chloride increase oxidative stress in the tear film.