Spending dinner in the bright, stopping at a red light or looking at a screen made of thousands of dots of light: These things are part of our daily routine. On May 16, UNESCO is celebrating the role of light in society with the International Day of Light for the third time. Less visible – but therefore no less important – is the role of light in medicine. After all, good visibility for doctors can make the difference between life and death.
The first attempt to bring light into the human body was made by Philipp Bozzini more than 200 years ago. He invented the “light guide”, an instrument consisting of a candle, a tube and a mirror with which he could illuminate the inner cavities of the human body. A little later, the “eye-mirror”, which was worn on a headband, was to reflect light in such a way that the doctor would not cast a shadow on his patient. Today it is hard to imagine examinations and operations without light: Thanks to endoscopes that conduct light and images in high quality via glass fibres, it is easier to examine the respiratory and digestive tracts and to detect diseases at an early stage. Minimally invasive operations such as appendectomies are possible. Where surgeons once had to make a cut, they now operate through three tiny wounds. At the dentist, fillings are hardened with blue light and cancerous tissue can be irradiated more specifically thanks to laser diffusers. After operations, light can create a relaxing atmosphere and help patients to heal.