Fluorescein sodium is a sodium salt and an organic fluorescent dye with peak excitation at 494 nm and peak emission at 512 nm. It has been safely used in humans for many years, predominantly in ophthalmology for retinal angiography, and the cost of fluorescein sodium is relatively low when compared with the cost of other agents such as 5-ALA. 

Medical Uses

Fluorescein sodium is usually visible to the naked eye at high dosages (20 mg/kg body weight) and is observable with a yellow 560 nm filter at lower doses, allowing better tissue discrimination with more natural colors.

Ophthalmology

Fluorescein sodium is mainly used as a tool of diagnosis in the fields of optometry and ophthalmology.  Fluorescein angiography stains the blood vessels of the retina and iris to give out a detailed image of the posterior view of the eye.

Bioimaging

Fluorescein’s extraordinary fluorescence helps for the detailed understanding of tumour-affected tissues, non-diseased tissues, and histological markers. 

Fluorescein angiography

The medical procedure which involves the injection of fluorescent dyes into the bloodstream of the body is known as fluorescein angiography.

Biochemical research

In the applications of fluorescence microscopy, the isothiocyanate derivative of the fluorescein is mostly put to use to track and label the cells in the biology of cells.