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.
How the test is performed: A piece of blotting paper containing fluorescein 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 abnormalities in the surface of the cornea will be stained by the dye and appear green under the blue light.
The ophthalmologist or optometrist (eye doctor) can determine the location and probable 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 contact lenses before the test.
For infants and children:
The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:
How the test will feel: If eyes are extremely 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 useful in identifying superficial scratches or other problems with the surface of the cornea. It can also help reveal foreign bodies on the eye surface. It can be used after contacts are prescribed to determine if there is irritation of the surface of the cornea.
Normal Values: If the test result is normal, the dye remains in the tear film on the surface of the eye and does not adhere to the eye itself.
What abnormal results mean: - corneal abrasion (a scratch on the surface of the cornea)
- infection
- injury or trauma
- foreign bodies, such as eyelashes or dust (see eye - foreign object in)
- Abnormal tear production (dry eye)
- Severe dry eye associated with arthritis (keratoconjunctivitis sicca)
Additional conditions under which the test may be performed:
What the risks are: If the fluorescein touches the skin surface, there may be a slight, brief, discoloration.
Special considerations: This test is very useful for detecting injuries or abnormalities on the surface of the cornea.
