This is a test that uses orange dye (fluorescein) and a blue light to detect foreign bodies in the eye. This test can also detect damage to the cornea, the outer surface of the eye.

A piece of blotting paper containing the dye will be touched to the surface of your eye. You will be asked to blink. Blinking spreads the dye around and coats the "tear film" covering the surface of the cornea. (The tear film contains water, oil, and mucus to protect and lubricate the eye.)

A blue light is then directed at your eye. Any problems on the surface of the cornea will be stained by the dye and appear green under the blue light.

The health care provider can determine the location and likely cause of the cornea problem depending on the size, location, and shape of the staining.

You will need to remove your contact lenses before the test.

If eyes are extremely dry, the blotting paper may be slightly scratchy. The dye may cause a mild and brief stinging sensation.