A Woods Lamp is a diagnostic tool used in dermatology to detect several conditions affecting the skin, including Vitiligo spots (and other skin and scalp diseases), Bacterial infections, Fungal infections, and Porphyria. NOTE: This is a lamp used for inspection and detection only and is not a therapeutic or treatment device.
Wood's Lamp or Wood's Light is a test invented by an American Physicist Robert Wood (1868-1955) that utilizes ultraviolet light to closely look at the skin. It is often referred to as Black Light and UV Light as well since it is invisible to the eye. The test is done while you are seated in a dark room, usually in the office of a dermatologist. The health care provider turns on the Woods Lamp, holds it 4 to 5 inches from the area of skin being studied, and looks for any skin color changes. It is advised that you should not look directly into the light. During the test, the person being examined shall feel nothing. No special preparation is needed for this test. If you are treating the area in question with any topical medications, you may wish to skip an application before visiting the doctor. Also, do not wash before the test, because that may cause a false-negative result. Results of the test may be altered due to the lighting of a room. The room has to be dark enough for accurate results. Other materials may also glow. For example, some deodorants, make-ups, soaps, and even lint may be visible with the Wood's lamp. However, please keep in mind that not all types of bacteria and fungi can be detected with the light.
If the person being examined has no bacterial or fungal infections and is normal, then his/her skin will not shine, or fluoresce, under the ultraviolet light. If light- or dark-colored spots occur on his/her skin during the Woods Lamp test then that means the patient has either of the skin diseases, and the doctor can then closely examine that skin disease.