Wajid Hussain Barki, Muhammad Fareed Ullah, Muhammad Zubair, Muhammad Tahir.
Effects of Benzalkonium Chloride on the Microanatomy of Corneal Stroma.
Annals Punjab Med Coll Jan ;8(1):11-5.

Benzalkonium chloride (BAC) is a commonly used preservative in topical ophthalmic preparations. It is a cytotoxic compound. The mechanism of action involves dissociation of bilaminar plasma membrane and its tendency to dissolve cholesterol, phospholipids and the proteins in the cell membrane. The indiscriminate use of eye drops containing BAC, quackery and self-medication may increase the incidence of corneal disorders particularly in those having a pre-existing corneal pathology. Objective: The present in vivo study was carried out to investigate the effects of BAC ons corneal stromaMethods: Two different concentrations (0.02% and 0.0075%) of BAC solution comparable to those present in the commercially available eye drops were prepared in isotonic saline. Right eye of each animal was treated with BAC solution while left eye of the same animal served as a control treated with normal saline alone. Results: The analysis of the results revealed significant (p<0.05) histological changes in the corneal stroma. Conclusion: This study has provided the convincing evidence that BAC is toxic to the corneal stroma and is a factor contributing towards visual impairment. 

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