VEGF-induced corneal neovascularisation in a rabbit experimental model.

INTRODUCTION AND PURPOSE Various conditions may cause vascularization of the normally avascular cornea. The aim of the present study was to create a reproducible experimental model that could enable the investigation of the phenomena leading to corneal vascularization. This involved creating a software to record the experimental data, enabling a subsequent digital analysis based on the growth models. The VEGF-induced pattern of neovascularization was also investigated. MATERIAL AND METHODS Twenty-seven rabbits divided in groups were used for the purposes of the present study. Some of them underwent intracorneal implants with or without vascular endothelial growth factor (VEGF) pellets, using an original microsurgical technique. Central and peripheral corneal burns were induced to other groups of animals in order to mimic the neovascularization process induced by inflammation. Finally, Dexamethasone (Maxidex) was given intraocularly, on days 1 and 3 after the onset of neovascularisation, in rabbit groups with both corneal burns and VEGF-implants. Video recording and data analysis of the corneal vascularization were made with an advanced biomicroscope, a computerized imaging system and a special software. A histochemical study of the animals' eyes was also carried out. RESULTS AND DISCUSSION The recorded data showed the simplicity and reproducibility of the present experimental model. The results showed the importance of VEGF as an initiator and promoter of corneal vascularization through a non-inflammatory mechanism, quite different from the inflammation illustrated by the corneal burn. At the same time, Dexamethasone therapy proved its effectiveness in corneal angiogenesis induced by thermal burn, but not by VEGF-implant.