Optical coherence tomography (OCT) is a precise technology that can be used for interrogating tissue structure and function noninvasively, painlessly, and quickly using near-infrared light. At its inception, OCT was typically a tool for assessing tissue thickness. Time-domain OCT is fast enough to scan a circle centered on the optic nerve head (circumpapillary) to assess retinal nerve fiber layer (RNFL) thickness. With the development of spectral-domain OCT, volumetric (3-dimensional) scanning becomes feasible.
Schuman JS. Optical Coherence Tomography in High Myopia. JAMA Ophthalmol. 2016;134(9):1040. doi:10.1001/jamaophthalmol.2016.2017