J Korean Ophthalmol Soc.  2002 Jan;43(1):189-196.

The Concentration of Benzalkonium Chloride in Aqueous Humor According to Size of Deepithelized Area of Rabbit Cornea

• Jin KH
• Kim DJ
• Lee SJ

Abstract

PURPOSE: To investigate the concentration of benzalkonium chloride (BAC) in aqueous humor and the cytotoxicity of corneal endothelium according to BAC concentrations of instillation and sizes of deepithelized area.
METHODS
Three experiments were performed: (I) After instillation of 0.02%, 0.05% and 0.1% of BAC (1cc, 15 drops during 30 minutes, 1 drop per 2 minutes) on normal cornea (24 eyes each), concentrations of BAC in aqueous humor were measured in 10, 30, 60, 120 minutes by HPLC; (II) After instillation of 0.02% and 0.1% of BAC on deepithelized cornea (2 and 5 mm in diameter), the same measurement was done in 60 minutes (6 replicates); (III) Corneas from both I and II were examined under transmission electron microscope (TEM) at 60 minutes following instillation.
RESULTS
The concentrations of BAC in aqueous humor were increased with time until 60 minutes (approximately 1/1000 of instilled concentration) and then decreased. The higher the concentration of BAC instillated and the larger the deepithelized area are, the higher the concentration of BAC in aqueous humor were measured (P<0.05, Wilcoxon rank sum test). According to the TEM, endothelial cellular damage was detected on both normal and deepithelized cornea and BAC concentration in aqueous humor was 0.52+/-0.13microgram/ml in the case of 0.05% BAC. In the case of 0.1% BAC, irreverisible endothelial cellular necrosis was visible on both normal and deepithelized cornea, and BAC concentrations in aqueous humor were 1.06+/-0.61microgram/ml (normal cornea), 1.37+/-0.85microgram/ml (2 mm deepithelized cornea), and 3.49+/-1.39microgram/ml (5 mm deepithelized cornea).
CONCLUSIONS
Even the clinically used low concentration of BAC may cause endothelial damages, especially in the absence of epithelial barrier. Therefore great care is warranted when the topicals containing BAC are applied to the largely erosive cornea.

Keyword

Benzalkonium chloride; Deepithelized cornea; Endothelium

MeSH Terms

Aqueous Humor*
Benzalkonium Compounds*
Chromatography, High Pressure Liquid
Cornea*
Endothelium
Endothelium, Corneal
Necrosis
Benzalkonium Compounds