Why should topical azithromycin be discontinued in contact lens wear?

• A. Because it contains benzalkonium chloride (BAK) in the bottle
• B. It causes rapid corneal melt
• C. It increases intraocular pressure
• D. It is ineffective against bacteria

Answer: (A)

The key idea is the preservative in the eye drop. Topical azithromycin formulations use benzalkonium chloride (BAK) as a preservative, and this compound can be toxic to the corneal surface with repeated exposure. Soft contact lenses readily absorb BAK, acting like a reservoir that concentrates the preservative and then releases it onto the eye, increasing irritation, surface toxicity, and lens intolerance. Because of this lens-related toxicity risk, discontinuing use during contact lens wear is advised. The other possibilities described aren’t the main issue here—rapid corneal melt, elevated intraocular pressure, or lack of antimicrobial activity aren’t typical concerns with azithromycin in lens wear.