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 cornea is the outer surface of the eye.
How the Test is Performed
A piece of blotting paper containing the dye is touched to the surface of your eye. You are asked to blink. Blinking spreads the dye 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.
The health care provider then shines a blue light 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 provider can determine the location and likely cause of the cornea problem depending on the size, location, and shape of the staining.
How to Prepare for the Test
You will need to remove your eyeglasses or contact lenses before the test.
How the Test will Feel
If your eyes are very dry, the blotting paper may be slightly scratchy. The dye may cause a mild and brief stinging sensation.
Why the Test is Performed
This test is to:
Find scratches or other problems with the surface of the cornea
Reveal foreign bodies on the eye surface
Determine if there is irritation of the cornea after contacts are prescribed
If the test result is normal, the dye remains in the tear film on the surface of the eye and does not stick to the eye itself.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.