Wood lamp examination is a diagnostic
test in which the skin or hair is examined while exposed to the
black light emitted by Wood lamp. Black light is invisible to
the naked eye because it is in the ultraviolet spectrum, with
wavelength just shorter than the colour violet. The lamp glows
violet in a dark environment, because it also emits some light
in the violet part of the electromagnetic
spectrum.
A traditional Wood lamp is a
low-output mercury arc covered by a Wood filter (barium
silicate and 9% nickel oxide), and emits wavelength *****0 nm
(peak **5 nm). This was invented in ***3 by a Caltimore
physicist, Robert W. Wood.
Ideally, skin to be examined should not
have been recently washed or had any makeup,
deodorant or moisturising cream
applied, as these can fluorescence causing a false positive
result
2. Gentle facial skin cleansing may be
required
Wood lamp is turned on to warm up for
about a minute
Room lights are turned off and window
shades drawn or black drape used to completely darken the
surroundings
After waiting to adapt to the dark, the
skin is examined with Wood lamp for a few seconds. The lamp is
held about ****0 cm away from the skin. Examination is painless
and safe.
