OCT Optical Coherence Tomography

Cross sectional imaging of the retina using light

Overview

Optical coherence tomography, OCT, is a noninvasive imaging technique that uses low coherence interferometry with near infrared light to produce cross sectional images of tissue at micrometer resolution, analogous to ultrasound but using light instead of sound. It was described in 1991 by a group at the Massachusetts Institute of Technology including David Huang and James Fujimoto, and ophthalmology became its first major clinical application. In the eye, OCT images the layers of the retina, the optic nerve head, and the anterior segment without contact and within seconds. It is central to the diagnosis and monitoring of macular degeneration, diabetic macular edema, macular holes, epiretinal membranes, central serous chorioretinopathy, and glaucoma, in which it measures thinning of the retinal nerve fiber and ganglion cell layers. Advances from time domain to spectral domain and swept source systems greatly increased speed and resolution. OCT angiography detects blood flow by analyzing changes between repeated scans, imaging retinal and choroidal vessels without injected dye.