How does this knife-like light cut, alter and repair our bodies?

WORDS AILSA HARVEY

DID YOU KNOW? The first laser surgery on a patient’s eyes was carried out in 1987

A laser – which stands for light amplification by stimulated emission of radiation – is a source of light that can be used for a variety of applications in surgery. Laser light differs from from that which you encounter in everyday life. Naturally occurring light from the Sun, or artificial light from a light bulb, emits a range of wavelengths of light, travelling in many different directions.Laser light, however, is polarised, focusing a beam onto one precise location.

In medicine, the laser wavelength is selected based on the aim of surgery. Some lasers, such as erbium lasers, are ideal for cutting body tissue, but aren’t as useful for sealing torn tissue. This method, called coagulation, uses heat produced by the laser to either destroy the cells or attach two pieces of tissue together.

As different wavelengths of light come into contact with different types of tissues and skin, they respond in different ways. Light can be reflected, scattered or absorbed by the body’s cells, while other times lasers pass right through the skin. Chromophores, which are molecules in the body that absorb particular wavelengths, cause them to present a specific colour. These molecules absorb more of the light during laser surgery. Examples of chromophores in the human body are haemoglobin and melanin. Absorption in these areas can cause physical, chemical and temperature changes. Using lasers instead of surgical instruments has many benefits. For example, lasers can reduce the risk of damage to surrounding tissues. After laser surgery, stitches are less likely to be needed, bleeding is reduced and the healing time for some operations is much shorter.