The dose-dependent effect of
epidermal growth factor (
EGF) on the development of
wound tensile strength following full-thickness corneal
wounds was evaluated in 60 adult rabbits. One eye from each rabbit received a single 7-mm long corneal incision. After injury each rabbit was treated three times daily for 5 or 10 days with either
EGF at 0.001 mg/ml (10 eyes), 0.01 mg/ml (10 eyes), 0.1 mg/ml (10 eyes), 1.0 mg/ml (15 eyes), or vehicle (15 eyes). The tensile strength of the
wound was evaluated using a 5-mm wide strip of cornea mounted on a tensiometer. We found that
EGF at 0.1 mg/ml and at 0.01 mg/ml increased
wound strength by 100% at 5 days and by 60%
at 10 days (P less than 0.05 and P less than 0.05). However,
EGF at 0.001 mg/ml and 1.0 mg/ml appeared to have no effect on
wound strength. Histologic examination of full-thickness
wounds in a separate series showed an increase in
wound fibroblastic response and a diminished
fibrin clot at 5 days in rabbits treated with 0.1 mg/ml and 0.01 mg/ml. We conclude that
EGF enhances the
wound strength of full-thickness corneal
wounds in a dose-dependent manner which may be explained in part by an increased fibroblastic response. Concentrations of
EGF greater or less than an optimal dose may be less effective in enhancing corneal
wound strength.