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Wood's lamp How the Test is Performed:
You will be seated, and the lights will be turned off. After your eyes adjust to the darkness, the Wood's lamp is turned on and held 4 to 5 inches from the area being studied. Take care not to look directly into the light.
How to Prepare:
It is important not to bathe or shampoo for 24-hours before your test, because porphyrins (a substance found in the suspect organisms) are removed with soap and water.
How it Feels:
The test involves sitting while your health care provider shines the ultraviolet light over the skin being studied.
Risks:
There are no risks, but avoid looking directly into the ultraviolet light, as you avoid looking into the sun.
Why this Test is Performed:
Your health care provider may perform this test to detect several conditions, including:
Normal Values:
Normally your skin will not fluoresce, or shine under the ultraviolet light.
Abnormal Results:
Under the ultraviolet light, different infections and conditions show different colors: - golden yellow ( Tinea versicolor)
- pale green (trichophyton schoenleini)
- bright yellowgreen (Microsporum audouini or M. canis)
- aquagreen to blue (Pseudomonas aeruginosa)
- pink to pinkorange ( Porphyria cutanea tarda)
- ash-leaf-shaped spot (Tuberous sclerosis)
- bluewhite ( Leprosy )
- pale white ( hypopigmentation )
- purplebrown ( hyperpigmentation )
- cold, bright white, or bluewhite (depigmentation, vitiligo )
- cold, bright white ( albinism )
- coralred, pink ( erythrasma )
Cost:
Information not available.
Special Considerations:
Washing before the test may cause a false negative result. A room that is not dark enough may also alter results. Other materials may alter results. For example, deodorants , make-up, tetracycline and soaps in the sweat may fluoresce. Some species of tinea capitis lack porphyrins and therefore will not fluoresce
A Wood's lamp is a light that uses long wave ultraviolet light. When an area of scalp that is infected with tinea (a type of ringworm fungus) is viewed under a Wood's light, the fungus glows (fluoresces). This test may be done to detect the presence of a fungal scalp or skin infection.
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