Final answer:
Fluorescein staining is used to detect corneal scratches, foreign bodies, and patency of the nasolacrimal duct. It involves the application of fluorescein dye and the use of a cobalt-blue light to reveal any abnormalities or blockages.
Step-by-step explanation:
The technique used to detect corneal scratches, foreign bodies, and the patency of the nasolacrimal duct is called fluorescein staining. Fluorescein is a dye that when applied to the eye, binds to damaged epithelial cells and reveals any abnormalities or blockages.
In this procedure, a fluorescein strip is moistened and gently touched to the eye's surface, allowing the dye to spread over the cornea and into the lacrimal puncta. A cobalt-blue light is then shone onto the eye, causing the dye to emit a green fluorescence, making any scratches, foreign bodies, or blockages visible.
Fluorescein staining is a valuable diagnostic tool for eye care professionals, helping them determine the extent of corneal damage and assess the integrity of the nasolacrimal duct.