Description General description Fluorescein dye is the most commonly used fluorescent probe. It is used to stain epithelial defects and analyse the integrity of corneal epithelium. Fluorescein is used in the diagnosis of corneal perforation. Oral or intravenous fluorescein is used in fluorescein angiography to detect diabetic retinopathy and choroidal neovascular membrane. Application Fluorescein has been used: • in the permeability assay of Caco-2 cells • to test its suitability to serve as lifetime fluorescence standards • as a fluorophore for the fast recovery of fluorescence peaks and fluorophore concentration in the presence of hemoglobin • as a fluorescent probe in oxygen radical absorbance capacity (ORAC) assay