Page 78 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
 Hence, we can deposit light, and therefore heat, energy into blood vessels preferentially (as long as they contain haemoglobin) without damaging all the other skin components.
This is the ‘selective’ part of Selective Photothermolysis.
Melanin
● Melanin is the pigment found in the superficial layers of the skin, particularly the epidermis. Black people have very high concentrations of melanin whereas Scandinavians have very little.
● Melanin contributes to our natural skin colour, but it also prevents harmful UV light from reaching the dermis.
● This is potentially harmful because the high-energy UV photons can alter the structure of DNA within cells. This can lead to cancerous growths, which explains why too much sun tanning is bad for us.
Figure 42: Various types of skin cancer – click on the above image to learn more
● For this reason, melanin has a wide absorption band. It absorbs all visible light to a certain degree, much moreso in the blue +UVA +UVB end to prevent damaging blue photon from entering the dermis.
● Hence, we can utilise most visible laser wavelengths and all IPL wavelengths to target the melanin. This is useful to treat benign pigmented lesions and similar brown skin spots.
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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