Purpose

To evaluate the impact of lubricant eyedrops on the corneal healing process and corneal toxicity.

Methods

Optive^® and Cationorm^® were tested regarding corneal irritability against Vismed Multi^® and 0.01% benzalkonium chloride as negative and positive control, respectively. Formulas were applied on rabbit corneas (n = 5) cultured on artificial anterior chambers (EVEIT system) hourly over 3 days. Initially, 4 corneal abrasions (2–5.4 mm²) were induced. All defects were monitored during drug application by fluorescein stains and photographs. To ensure corneal vitality, glucose and lactate concentrations were determined photometrically in artificial anterior chamber fluids. Corneal fluorescein sodium permeability was tested as an indicator of the corneal barrier function.

Results

Optive^® and Vismed Multi^® showed a complete corneal healing on day 2. In one cornea (Optive^®), erosion reoccurred on day 3. Erosion sizes of Cationorm^®-treated corneas increased significantly from 12.20 mm² to a subtotal erosion of 51.89 mm² on day 3. Histology revealed epithelial loss and severe alterations of the superficial stroma for Cationorm^®. Glucose and lactate concentrations did not change after application of Optive^® and Vismed Multi^®. In contrast, Cationorm^®- and BAC-treated corneas showed a significant increase in lactate concentrations.

Conclusions

Vismed Multi^® application resulted in rapid corneal healing. Whether the toxicity seen for Optive^® in one cornea is a valid result should be examined further. Cationorm^® showed considerable corneal toxicity that could be caused by its additive, cetalkonium chloride. Otherwise, the electrostatic properties of Cationorm^® led to a drug film on the area of epithelial loss that could hinder epithelial cell migration and adhesion in order to heal the lesion.