Optical Coherence Tomography (OCT): principles of operation, technology, indications in vitreoretinal imaging and interpretation of results

Optical coherence tomography (OCT) is a relatively new non-contact, non-invasive technique for in vivo examination of the human retina. It is based on the Michaelson interferometer. It is analogous to B-scan ultrasound except that it measures optical rather than acoustic reflectivity. It has a depth resolution of approx. 10 µm compared to 150 µm of B-scan ultrasound. High-frequency ultrasound has a resolution of approximately 20 µm, but due to the limited penetration of 4 mm it can only be applied to the anterior segment. Neither computed tomography nor magnetic resonance imaging achieve a similar resolution to that of OCT.