Top 9 Medical Diagnostic Applications for a Woods Lamp

Normal, healthy skin looks purple or violet during a Woods lamp examination and will not glow. This allows fungal and bacterial colonies to stand out since they will naturally fluoresce under the ultraviolet light.

Depending on the skin condition revealed, fluorescence can appear as golden yellow, pale green, aqua, pink-orange, blue-white, or even purple-brown.

1. Tinea Capitis

Tinea capitis describes a condition in which the skin presents with areas of scale and baldness as a result of a fungal infection. It was the first skin condition for which the Woods lamp was historically used to diagnose. Woods lamp diagnosis is not only effective for identifying individual cases of tinea capitis, but also for detecting and controlling large epidemics, such as within schools. However, it is important for your team to keep in mind that tinea capitis fluoresces in only 5 percent or fewer of cases in the United States. When it does, it presents typically as blue-green, although it can occasionally manifest as dull yellow or dull blue. However, other fungal infections related to different microorganisms do not necessarily fluoresce.

2. Vitiligo

A Woods lamp examination is especially helpful in making a diagnosis of vitiligo – especially if it must be differentiated from other conditions like leprosy, pityriasis or post-inflammatory hypopigmentation. The lamp also helps illuminate evolving lesions in a fair-skinned patient. Vitiligo appears as white patches under a Woods lamp, which varies in both location and extent. These patches may also spread and grow over time. Examining under a Woods lamp can give your health care team complete visual information regarding the progress of a patient's vitiligo.

3. Corneal Abrasions

To look for scratches on the eye, the medical professional must first put a fluorescein solution in the patient's eye before using the Woods lamp to illuminate the eye area – any scratches or abrasions will subsequently glow when the ultraviolet light hits them. During an eye exam, a Woods lamp can help identify foreign particles within the eye, even glass and other hard-to-see particles, plus illuminating injuries and even blocked tear ducts.

4. Ringworm

This fungal culture, which often affects the skin, hair, and nails, is easily detected and/or confirmed using a Woods lamp. The use of a Woods lamp to test for ringworm is especially common within veterinary practices, as the infection presents often among animals. Under the Woods lamp, the ringworm infection fluoresces as bright apple green.

5. Porphyria

Porphyria is a group of inherited disorders that cause rashes, blistering, and scarring of the skin. When examined under a Woods lamp, they all fluoresce as red-pink. In fact, detecting and identifying excess porphyrins in urine, teeth, red blood cells, stool samples and even blister fluid can easily be achieved when using a Wood's lamp.

6. Pigment Disorders

Hypopigmentation or depigmentation can be difficult to discern in the fairest-skinned of patients, but they demonstrate increased border sharpness when examined using a Woods lamp; they generally fluoresce as a bright blue-white because of the increased amount of dermal collagen being illuminated, which is a result of either decreased or absent intervening melanin. Conversely, hyperpigmentation presents with enhanced border contrast under a Woods lamp because of the increased absorption of light related to increased levels of melanin. Using a Woods lamp can help determine the level of melanin within the skin, along with clearly highlighting variations in epidermal pigmentation.

7. Bacterial Infections

Infections from pathogens like Pseudomonas can appear as a bright green fluorescence under a Woods lamp. This method is often used to examine burn wounds for bacteria and also is helpful in the diagnosis of Stevens-Johnson syndrome.

8. Acne Vulgaris

Orange-red fluorescence is associated with any comedones infected with P. acnes. This can help the health care professional determine which, if any, comedones are the result of infection.

9. Other Miscellaneous Uses

  • Other uses of the Woods lamp in health care include the following:
  • Detection of systemic drugs like tetracycline
  • Efficacy assessment of the sun protection factor of various sunscreens on the market
  • Detection of skin allergens
  • Calculation of circulation time
  • Treatment of warts, with some success
  • Detection and treatment of skin cancer, with some success