Wood’s lamp what is it?
Wood’s lamp has been used in dermatology for many years. It was conceived in 1935 by physicist Robert Wiliams Wood and consists of a special lamp in which the glass tube is totally colored purple.
The coloring is done through metal oxides, in order to retain part of the visible radiation and to produce an ultraviolet light, invisible to the human eye.
The lamp emits a particular non-ionizing ultraviolet light, not dangerous, in the UVA band.
Examination with Wood’s lamp
The exam is totally painless and non-invasive. It happens by illuminating bare skin with this ultraviolet light.
In order for the exam to be successful it is necessary to perform the exam in a darkened room. Only in this way is vitiligo fully visible.
Wood’s light can detect pigmented or depigmented areas of the skin and can also detect fluorescence.
Under the light of Wood’s lamp normal, healthy skin appears blue in color, but may show white patches when the skin is thick and yellow when it is oily. Purple spots indicate dryness or dehydration.
A positive result of the presence of vitiligo is when there is an obvious pigmentation disorder or fluorescence is noted.
What is it used for?
Wood’s lamp is used to select infected skin and hair for laboratory investigations. It can also detect skin disorders, including vitiligo and other skin irregularities.
Wood’s light can be used to diagnose the following disorders:
- pigmentation disorders such as vitiligo and melasma
- pityriasis versicolor, the rash will be orange in this case
- areas of baldness, and will exhibit blue-green fluorescence
- scabies and lice
The lamp can also be used to determine if the patient has a corneal abrasion on the surface of the eye.