Effect of topical administration of epidermal growth factor on healing of corneal epithelial defects in horses.

This study investigates how the healing of corneal epithelial defects in horses is affected by the application of epidermal growth factor (EGF). The research concluded that while high doses of EGF can accelerate healing, this benefit is outweighed by the resulting intense inflammatory response.

Study Methodology

• The researchers created corneal epithelial wounds in 20 eyes across 12 adult horses by mechanically debriding the limbus.
• They divided the eyes into three treatment groups. Five eyes received 50 microg/ml of EGF, seven eyes received 5 microg/ml of EGF, and eight eyes were treated with PBS solution as a control.
• The healing progress was recorded daily through photography after instilling a fluorescein stain and the wound area was calculated using imaging software.

Results

• The study found that after corneal debridement, re-epithelialization (healing of the eye surface) was rapid and linear for the first five to seven days in all groups.
• After this period, the rate of healing decreased across all groups.
• The researchers observed a significant increase in inflammation, neovascularization (formation of new blood vessels), melanosis (dark pigmentation), and scarring in eyes treated with the high dosage of EGF.
• Despite these effects, there was no statistical difference in average healing times or decrease in wound radius during the linear phase between the control group and either EGF treated groups.
• In cases where both eyes of a horse were treated, the first eye healed significantly faster than the second, regardless of the treatment used.

Conclusions

• Applying a high dose of EGF can accelerate healing of corneal defects, but this is overshadowed by the severe inflammatory response that accompanies it.
• Surprisingly, the healing time was not significantly different between the control group and the EGF treated groups, suggesting that while EGF may speed up initial healing, the overall recovery time is not affected.
• The faster healing of the first eye compared to the second in each horse could point towards systemic factors influencing healing time, or perhaps a stress response to the initial procedure, however further research would be required to determine this.