As we grow older, our skin ages due to both internal, genetic factors and environmental factors such as sunlight. This mishmash of effects can make telling the real age of someone’s skin very difficult, as sunlight can cause premature ageing and mask the natural ageing process.
Now, researchers have pioneered a way to tease out this information. Their ‘virtual biopsy’ works by firing a quick and painless infrared laser pulse at the skin. This penetrates about 0.3mm through the outermost layer of the skin – the epidermis – and into the dermis layer below.
The researchers then create 3D maps of the skin’s structure by using a microscope to study how the laser light interacts with the skin cells. This technique is called ‘harmonic generation biopsy’ because it analyses the second and third harmonics of the light – oscillations with two or three times the frequency of the original light.
They tested their method on 52 volunteers, pointing the laser at the volunteers’ inner forearms, which are usually shielded from the Sun and so only age via natural processes.
They found that the size of a certain type of skin cell called basal keratinocytes increased with age. So, by monitoring these cells, the scientists say that they could measure the natural age of someone’s skin.
This would be useful for testing the performance of anti-ageing products (by finding out whether they can actually help to slow the skin’s ageing process), as well as for tracking the progress of skin diseases.