Benzalkonium chloride toxicity to the human cornea

Area of Science:

• Ophthalmology
• Toxicology
• Materials Science

Background:

• Soft contact lenses are commonly used for vision correction after cataract surgery.
• Lens care solutions are essential for maintaining lens hygiene and patient safety.
• Previous studies have indicated potential toxicity of certain preservatives in contact lens solutions.

Observation:

• A 36-year-old woman developed acute eye inflammation and decreased vision after switching to a new contact lens solution.
• The new solution contained boric acid, potassium chloride, sodium carbonate, benzalkonium chloride, and edetic acid.
• Clinical examination revealed anterior chamber inflammation (2+ cell and flare) without endothelial damage.

Findings:

• The patient's symptoms resolved after discontinuing the use of the implicated contact lens solution and lens.
• Laboratory analysis, including a semiquantitative dilution method, confirmed the cytotoxic effects of benzalkonium chloride.
• The preservative benzalkonium chloride was identified as the causative agent for the observed ocular toxicity.

Implications:

• This case highlights the critical importance of preservative selection in soft contact lens solutions.
• Ocular surface toxicity from preservatives like benzalkonium chloride can lead to significant visual impairment.
• Further research is warranted to develop safer and equally effective preservatives for contact lens care products.