Non-invasive technology that was originally used in ophthalmology, but has also gained importance for dermatological diagnostics since 1997. Physically, OCT is based on the principle of interferometry: coherent light waves are projected onto a tissue, in this case the skin - the delay or intensity of the reflections is measured on the basis of the interference behavior at the various layers. In contrast to laser scanning microscopy, OCT uses an infrared laser beam (wavelength 1300 nm) to scan the skin. By delaying and intensifying the reflection of the coherent light waves at interfaces of different structures with correspondingly different refractive index, a three-dimensional image of the skin can be generated in real time. This reconstruction is called tomography. The infrared signal penetrates up to 1.5 mm into the skin, i.e. much deeper than in laser scanning microscopy.
In dermatology, OCT is mainly used for early diagnosis of small non-specific skin tumors, both pigmented and non-pigmented. In addition, therapy planning - either spread of the tumor before surgery or control of conservative therapy measures is useful.