Medical Applications for UV Blacklight


Long wave ultraviolet (UV) 365nm light – commonly known as Black Light or Woods Light – has been used successfully by the medical profession for decades. The Fluorescent properties of diseased or damaged tissue and certain microorganisms have proven to be an invaluable diagnostic aid in many medical specialties.


When normal human skin is exposed to ultraviolet light, it fluoresces a dull or weak bluish white. Departures from this normal reaction can aid in the diagnosis of certain conditions affecting the skin.

Fungus Infections, such as ringworm or tricophyton, show as various shades of green (from yellowish to chartreuse) under ultraviolet light.

Tinea versicolor, a skin rash, will fluoresce yellow.

Vitamin B deficiencies will be indicated by the red fluorescence of a prepellagrinous tongue.

Subdermal wheals in chicken pox, measles, scarlet fever and urticaria will show negative fluorescence.

Erythrasma, a skin condition, will show bright red to coral under UV light.

Head Lice, which fluoresce a bluish white color, are commonly detected on students in schools with the use of a UV lamp.

Scabies, a contagious skin disease, is usually treated with topical tetracycline and then examined under ultraviolet light; the result is a yellow fluorescence.

Psoriasis, identified by itch and red patches covered by white scales, has for many years been treated by exposure to UV light.

Vitiligo, a disorder in which there is a loss of skin pigment, can be treated with exposure to ultraviolet light. The affected patches can also be more easily identified using UV light, especially in the case of fair-skinned people.

Scalp tinea, a microsporum, will cause hairs to fluoresce yellow under UV light.


Corneal scratches and abrasions, invisible to the naked eye, will fluoresce green in the scratched area after a fluorescein stain is put in the eye. Also disclosed under ultraviolet inspection are injurious foreign bodies such as metal or glass, as well as ulcerated areas and damaged conjunctiva.

Cataracts: The crystalline lens of the human eye has a natural fluorescence, therefore opacities caused by cataract growth or lenticular dislocation can be more easily observed under ultraviolet light.


Microsporum canis, a condition found in animals, is seen as greenish-yellow color under ultraviolet light.

Blocked tear ducts are identified by putting a fluorescein stain in the eye of the animal and inspecting the nasal cavity. If no stain is detected there using UV light, the veterinarian should treat for a blocked tear duct.

Mite burrows can be detected by simple surface staining followed by inspection with UV light.


Burn Evaluation: An intravenous solution of sodium fluorescein will differentiate between a second or third degree burn.

Skin Grafting entails certain vascular prerequisites which can be determined by an intravenous solution of sodium fluorescein.

Testing blood circulation in various extremities can likewise be performed in the same manner as above.

Cardiology: A fluorescein dye in injected in the circulatory system and the gums are examined under ultraviolet light to determine circulation time.