The effect of anti-allergy eye drops on cultured human corneal epithelial cells in vitro

Ocular allergy is a global phenomenon that affects roughly 40% of allergy sufferers. Majority of cases will require the use of topical ophthalmic medication to treat symptoms of ocular allergy localised to the eye. Corneal ectasia, commonly known as keratoconus, is a disease where the rigidity of the cornea is compromised, leading to loss of form and function of the cornea as it deforms into a conelike shape. A common risk factor for keratoconus is the mechanical pressure applied when a patient rubs their eyes, an autonomic response to eye irritation and itching that can be induced by ocular allergy. The interaction between regular application of anti-allergy eyedrops and corneal ectasia is currently unknown. In this study, the cytotoxicity of common anti-allergy eyedrop active ingredients, as well as their common commercial preservative benzalkonium chloride (BAK), were observed at various concentrations on human corneal epithelial cell (HCEC) line at time points up to 5 days. After the timepoint treatment, MTT analysis and dot-immunobinding assay were performed on the cells to determine the cytotoxicity and production of corneal ectasia biomarkers matrix metalloproteinase (MMP-9), lysyl oxidase (LOX) and collagen type IV (COL-IV) in response totreatments. Results show that levocabastine, a preserved antihistamine was the only treatment with significant overall decrease in cell viability (P<0.001). Closer analysis revealed that ketotifen fumarate non-preserved, sodium cromoglycate, and olopatadine showed significant decrease in cell viability (P<0.05) at two or more concentrations compared to the no treatment control (0.00%) after 5 days of treatment. It was determined there was no significant decrease in cell viability with presence of BAK. Therefore, cells were perhaps affected by the active ingredients rather than the preservative itself. Analysis of protein biomarkers revealed decrease in LOX and COL-IV at higher concentrations of levocabastine after 5-days of treatment.