Wood’s light

Wood’s light is a lamp emitting long-wave UVA used to examine pigmentary changes in the skin and fluorescent infections. This ultraviolet light source is used to screen for the fungal infection, tinea capitis; however, only certain species fluoresce (green) (Microsporum canis and Μ. audouinii). Other uses include highlighting patches of pityriasis versicolor caused by Pityrosorum yeast which fluoresces yellow; erythrasma, a bacterial infection affecting the skin folds, caused by Corynebacterium fluoresces green and vitiligo which delineates patches which can be otherwise missed.