Wood's Lamp Examination

A Wood's lamp examination is a test that uses ultraviolet light to closely look at the skin.

MEDICAL USES

Several skin diseases/challenges such as vitiligo, acne and a host of others cause the skin (or the fluids on the skin) to fluoresce.

Vitiligo

Bacterial Infections

Acne

Porphyria

Erythasma

Alopecia

Tinea Versicolor

Fungus & Fungal Infections

Head Lice and their nits, fluoresce under black light

Ringworm

Scabies

Child abuse / bruising can often be discerned with a Woods light

Ophthalmology

When used with sodium fluorocein or other fluorescing dyes, there are several applications for the world of the eye doctor.

Foreign Particles in the Eye (glass and other hard to see particles)

Eye Injury

Scratches of the cornea

Blocked Tear Ducts

TECHNIQUE OF WOOD’S LAMP EXAMINATION

The use of a Wood’s lamp does not require great skill. However, some practical points should be kept in mind to avoid misinterpretation of results.

The lamp should ideally be allowed to warm up for about 1 minute.

The examination room should be perfectly dark, preferably a windowless room or a room with black occlusive shades.

The examiner should get dark adapted in order to see the contrast clearly.

The light source should be 4 to 5 inches from the lesion.

Washing the area before subjecting it for Wood’s lamp examination should be avoided since it may yield false negative results due to dilution of the pigment.

Topical medicaments, lint and soap residues shouldbe wiped off from the site to be examined since these may fluoresce under Wood’s light. Common sources of error are bluish or purplish fluorescence produced by ointments containing petrolatum,green fluorescence by salicylic acid containing medicaments, and light reflected from examiners white coat producing light blue fluorescence.