Optical Coherence Tomography: A Primer

Optical coherence tomography (OCT) is a non invasive, non contact transpupillary interferometric technique for real time in vivo imaging of retinal microstructures. It is equivalent to ultrasound B-mode imaging with use of light instead of sound. Spectral Domain-OCT utilizes a broadband optical source and a processing unit, spectrometer. Fourier domain transformation utilizes an array of detectors in place of a moving mirror, to acquire A-scan concurrently. This increases the scanning speed to about 200 times faster than time domain OCT. The high sampling density hence achieved produces high-quality individual B-scan images. With the advent of swept source OCT and enhanced depth imaging protocol even choroid can be imaged. OCT angiography identifies retinal circulation using the intrinsic motion of the blood cells in vessel.