Our latest podcast is about how light travels in the skin and the effects of ‘sideways’ scattering.
This is a real effect, which I wrote about before (here). I mentioned how red light can scatter out from the original spot area into the surrounding tissues. This can lead to problems if you’re treating hair, for example, near to a tattoo. If you get too close to the tattoo, some of the red light may reach it and cause unwanted damage.
I found that this had happened to one of our clients – Amy, from Arbroath in Scotland, who agreed to let me show you her tattoo. She had received some diode laser treatment to her leg hair. Unfortunately, the laser operator got just a bit too close to her tattoo.
This resulted in some permanent damage – this photo was taken around 20 months after the treatment.
We can see damage in the right-hand side of the tattoo. This damage is entirely due to the millisecond pulses of infrared laser light heating the tattoo ink particles. Since the pulses were so long (compared to nanosecond pulsewidths), the particles are heated slowly and then they released that heat energy into the surrounding collagen over the millisecond timescale.
This clearly raised the temperature of the local collagen to such a point where irreversible damage occurred – which led to scar formation.
So, be careful not to go too close to tattoos, or pigmentation, when carrying out laser/IPL hair removal – you might get more than you bargained for!!
Hope this helps,
Mike.
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