When tissues are illuminated with laser, light absorption occurs in the cell which has shown to affect cell functions positively. This can to some extent compared with photosynthesis in which plants receive sunlight. Very simply, one can say that illumination with laser light affects cells and tissue to heal.

The laser light is applied, in contact, to normal healthy skin. Sensitive or damaged skin and open sores are treated in a non-contact way, with the laser-aperture held at a distance of one to a few centimetres from the skin. In order to achieve a good, effective result the laser light needs to be able to penetrate the skin tissue and reach the area to be treated.

Infrared wavelengths such as 904 nm (super pulsed) and 808 nm have the best penetration-capacity and are therefore used on deep-lying problems e.g. joints and muscles. Lasers with visible wavelengths such as 660 nm, 520 nm and 450 nm have lesser penetration-capacity and are therefore used on superficial problems such as tendons, skin or sores.

When laser light is applied to skin or tissue it is absorbed, reflected and spread in various directions. The deeper the light penetrates the tissue, the weaker it becomes, therefore a larger amount of laser light energy is used when treating, for example, muscles and joints, as compared to open sores.