A Wood’s lamp, also known as a black light, is a diagnostic tool used in dermatology to detect certain skin disorders. It works by emitting ultraviolet (UV) light onto the skin, which can illuminate issues not visible under normal light. When observed under the light of the Wood’s lamp, different skin conditions can appear in specific colors, helping to identify potential problems.
Below are the colors typically seen under a Wood’s lamp and the skin conditions they often indicate:
- Normal skin: Normal skin usually does not fluoresce under the Wood’s lamp and generally appears as its natural skin tone.
- Blue-white or bright white: This color often indicates a fungal or bacterial infection. Vitiligo, a condition that causes loss of skin color in blotches, also appears as bright blue-white or bright white.
- Pale white: Pale white areas under a Wood’s lamp may suggest hypopigmentation, such as that resulting from scars, burns, or other forms of skin damage. Vitiligo, where the skin loses its pigment cells, can also appear as pale white.
- Yellow or orange: Certain types of acne may fluoresce yellow or orange under a Wood’s lamp. Some fungal infections can also appear in this color.
- Green: A green fluorescence often indicates a bacterial infection, such as Pseudomonas aeruginosa.
- Coral red: This distinct color is usually indicative of erythrasma, a bacterial infection that affects the skin’s top layers.
- Purple-brown: This color can signify hyperpigmentation, a condition where patches of skin become darker than the normal surrounding skin. It can also be associated with melasma, a similar condition that primarily affects women and is often associated with hormonal changes.
- An orangish color is indicative of oiliness on the skin or fat present at the opening of hair follicles.
The UV light emitted by a Wood’s lamp penetrates the skin. If a lesion or hyperpigmentation is located in the epidermis (the outermost layer of the skin), the light will hit this surface layer and bounce back without much diffusion. This results in a sharp, well-defined border for the lesion or hyperpigmented area under the Wood’s lamp. This sharp border indicates an epidermal lesion, which tends to be easier to treat.
However, if a lesion or hyperpigmentation is located deeper within the skin, specifically in the dermis layer, the UV light must pass through both the epidermis and the dermis. This journey causes the light to disperse, and the reflected light will be more diffused, resulting in a less defined, blurrier border of the lesion under the Wood’s lamp. In these cases, the lesion is likely in the dermis, and its treatment tends to be more challenging.
Having a Wood’s lamp in your treatment room is beneficial as it helps determine the depth of skin lesions and whether they fall within your professional scope of practice. Epidermal lesions are typically within the purview of skincare and beauty professionals. However, issues located in the dermis layer fall outside their professional capacity and should be referred to medical professionals for treatment.
Skin Scope
Skin Scope is a handheld device used for skin analysis that uses specialized lighting and magnification to examine the skin’s condition, including texture, pigmentation, and pore size. The device is commonly used by dermatologists, estheticians, and skincare professionals to assess and diagnose various skin conditions, such as acne, rosacea, and aging. The results of the skin analysis can be used to develop personalized skincare regimens and to track the effectiveness of treatments over time.