Widely used in medical diagnostics, especially in ophthalmology for fluorescein angiography to visualize blood flow in the retina and detect vascular abnormalities such as leaks, blockages, or new blood vessel formation. Commonly applied in eye exams to assess diabetic retinopathy, macular degeneration, and other retinal diseases. Used in dermatology and surgery as a fluorescent tracer to identify tissue perfusion and detect areas of poor blood flow during procedures. Employed in environmental studies to trace water movement, detect leaks in pipelines, and monitor groundwater flow due to its high visibility in low concentrations. Utilized in laboratory research as a fluorescent probe for microscopy, flow cytometry, and immunoassays because of its strong green fluorescence under UV or blue light. Also found in some cosmetic products and topical antiseptics as a coloring agent, though primarily valued for its safe and reversible staining properties.