Fluorescein, a synthetic organic compound with the chemical formula C20H12O5, is renowned for its fluorescent properties. It is a bright, intensely colored dye that exhibits strong green fluorescence when exposed to ultraviolet or blue light. This fluorescence makes Fluorescein a vital tool in various applications, particularly in medical diagnostics and ophthalmology. In ophthalmology, Fluorescein is commonly used in the form of eye drops to perform a fluorescein angiography, a diagnostic procedure that helps visualize the blood vessels in the retina. The fluorescent dye enhances the visibility of blood flow and detects any abnormalities or issues in the eye’s vascular system.

Fluorescein also has applications in the field of analytical chemistry as a pH indicator. It changes color depending on the pH of a solution, transitioning from yellow at low pH to bright red at high pH levels. This property is utilized in various chemical analyses and titrations to determine the acidity or alkalinity of a solution accurately. Moreover, Fluorescein is employed as a tracer dye in hydrological studies to track water flow and dispersion. Its ability to fluoresce under specific conditions and its versatility in various scientific and medical applications highlight its importance in research and diagnostics.