Wood’s lamp is a medical device used for making diagnoses, especially by dermatologists. How does it work? What diagnosis can be made with this lamp? Answers to your questions about Wood’s lamp.

A Wood’s lamp is a diagnostic tool, producing ultraviolet radiation. It is used in many fields. In dermatology, it is used to examine the skin of patients and to detect several types of skin problems. Many infections of the epidermis are in fact very inconspicuous or even invisible to the naked eye. Wood’s lamp is also used for diagnostics in aesthetics, ophthalmology, veterinary medicine, etc.

Composition

A Wood’s lamp is a lamp that produces ultraviolet (“black light”) illumination. The glass of this lamp is barium silicate containing 9% nickel oxide.

The wood lamp is mainly used in dermatology to detect:

• fungal infections of the hair;
• erythrasma;
• skin fungal infections;
• bacterial skin infections;
• pigmentation problems.

The skin should not glow or fluoresce from the rays. If so, the color of the fluorescence helps make a diagnosis.

Wood’s lamp indications

Wood’s lamp is used by healthcare professionals, and particularly dermatologists for:

• evaluate the degree of hydration of the skin and the thickness of the skin;
• diagnose dry areas, solar keratosis, seborrhea, acne, mycosis, hyper / hypopigmentations and vitiligo;
• diagnose erythrasma, skin fungal infections, bacterial skin infections and certain pigmented lesions;
• observe vitiligo spots and assess whether the melanocytic deficit is partial or total, and assess the real extent of Vitiligo;
• make the clinical diagnosis between a melanoma or melanocytic hyperplasia and a hematoma;
• evaluate pigmentary changes;
• diagnose ringworm in pets.

Public concerned or at risk

Wood’s lamp can be used to make diagnostics in humans but also in animals.

The stages of operation

This medical device is a manual device. The healthcare professional holds it in his hand, and places it about twenty centimeters from the area to be observed, in a room which must be in the dark. Depending on the color of the fluorescence, the healthcare professional can know which pathology it is. For example, yellow-green fluorescence is observed in microsporic moths, yellowish fluorescence is observed in lesions by Pityriasis versicolor, a coral pink fluorescence is observed in erythhasmas (infections caused by Corynebacteria).

When to use it?

Wood’s lamp is used by healthcare professionals. In dermatology, it is used to examine the skin and make diagnoses.

Precautions to take

Wood’s lamp should not be used in a humid atmosphere. Do not look directly at the light source to avoid any risk to the eyes.

Other uses

Wood’s lamp is used in many fields apart from health which remains the main field of use: graphology (analysis of writings, reading of difficult to read texts), mineralogy (tint of minerals), in chemistry, in the field of art (to see if there are repaints, restorations) and by banking and financial authorities (detection of counterfeit banknotes) and the scientific police.

History

Black light or Wood’s light was invented by Robert Williams Wood in 1903. This ultraviolet light was called “Wood’s glass”. It was applied from 1925 in dermatology, first of all to detect infections in the hair.