KohärenztomographieAngiografie

Kohärenztomographie, also known as optical coherence tomography (OCT) in German-language contexts, is an imaging modality that uses low-coherence interferometry to obtain micrometer-scale, cross-sectional images of biological tissues. It combines a broadband light source with a reference arm and a sample arm in a Michelson-type interferometer. By scanning the sample and recording interference spectra, OCT reconstructs depth-resolved reflectivity maps.

OCT was developed in the early 1990s, with time-domain OCT introduced by Huang and colleagues in 1991. The technique evolved into spectral-domain OCT in the 2000s, which uses Fourier-domain detection to achieve higher speed and sensitivity, and swept-source OCT, using tunable lasers for deeper penetration and longer imaging range. Wavelengths commonly span near-infrared regions around 800–1300 nm, chosen to balance scattering and penetration in tissue; 1050 nm and 1300 nm are prevalent for retinal imaging and other tissues.

Applications are diverse but OCT is most widely used in ophthalmology for imaging retina layers, optic nerve head, and corneal structures. It is also employed in dermatology, dentistry, cardiology, and industrial non-destructive testing. Advantages include non-invasive, label-free imaging with high resolution and real-time, three-dimensional capabilities. Limitations stem from light scattering, which limits penetration in highly scattering tissues, motion artifacts during in vivo imaging, and the need for careful alignment and interpretation. Safety is generally favorable, as OCT uses low-power, non-ionizing near-infrared light, with exposure within established limits.