How a Wood's lamp works
A Wood's lamp emits long-wave ultraviolet A (UVA) light, typically around 365nm, through a filtered glass lens. When held close to the skin in a darkened room, it causes different skin structures and pigment to fluoresce (glow) in characteristic patterns that aren't visible under ordinary light.
For pigmentation specifically, a Wood's lamp helps distinguish between epidermal pigmentation (in the upper skin layer, which fluoresces more distinctly and tends to respond well to topical treatment) and dermal pigmentation (deeper in the skin, which shows less contrast under the lamp and generally requires a more intensive treatment approach).
What a Wood's lamp examination is used for
Beyond pigmentation depth assessment, a Wood's lamp can help identify certain fungal skin infections and pigment or texture irregularities not otherwise visible — making it a useful general diagnostic tool during a skin consultation, not only for pigmentation cases.
The examination itself is quick, comfortable, and non-invasive — it takes only a few minutes as part of a broader consultation. It does not replace clinical judgement; rather, it adds useful information that helps guide an accurate diagnosis and appropriate treatment plan.