Wood’s Lamp Examination

What is a Wood’s lamp examination?

A Wood’s lamp examination is a straightforward test utilized for identifying specific skin, scalp, and hair conditions. It aids in diagnosing fungal, bacterial, and parasitic infections. This examination involves the use of long-wave ultraviolet (UV) light, which causes certain cells to display color or fluorescence.

This diagnostic tool, created by American physicist Robert Wood, is also referred to as:

• Blacklight test.
• Ultraviolet light test.
• Wood’s light test.

What can a Wood’s lamp diagnose?

A Wood’s lamp examination aids healthcare providers in diagnosing various disorders, including:

• Abnormal pigmentation conditions like melasma and vitiligo.
• Bacterial infections such as Pseudomonas and Corynebacterium.
• Corneal abrasions.
• Porphyria.
• Infestations like scabies and head lice.
• Skin fungal infections such as ringworm, tinea capitis (scalp ringworm), or tinea versicolor (yeast infection on the skin).
• Skin imperfections including acne, signs of aging, and milia.

What else can Wood’s light detect?

The Wood's lamp is also utilized for nonmedical purposes. For instance:

• Banks employ the tool to identify counterfeit money.
• Bouncers use it to verify hand stamps when patrons re-enter a bar or club.
• Immigration officers rely on it to authenticate passports.
• Law enforcement officers utilize it to detect urine or semen at crime scenes.
• Museums, jewelers, and scientists use the lamp to examine paintings, sculptures, minerals, and gems.

How does a Wood’s lamp work?

A Wood’s lamp emits ultraviolet (UV) light, commonly known as black light, which is invisible to the naked human eye. It also emits a small amount of light in the violet spectrum, which is visible without aids.

When this UV light illuminates the skin or other surfaces, certain cells exhibit distinct appearances. Specific colors indicate the presence of healthy skin, while other colors or a fluorescent glow may indicate the presence of unhealthy cells like fungus or bacteria.

What can I expect during the blacklight test?

A Wood’s lamp emits no heat and conducting the test is painless. Here are the steps your healthcare provider will follow during a Wood’s light examination:

• Ensure the room is completely dark by turning off overhead lights, closing window shades, or using a black drape over the skin.
• Turn on the Wood’s lamp, which will emit a faint glow.
• Allow about a minute for the lamp to warm up and for eyes to adjust to the darkness.
• Wear safety goggles or glasses for protection.
• Hold the lamp approximately 5 inches away from the skin and examine it for a few seconds.
• Turn off the lamp and switch on the room lights.
• Discuss the examination results with you.