History
Optical coherence tomography was first introduced commerically by Carl Zeiss in 1996. The first commerically available OCT was based on time-domain technology (TD). The Stratus TD-OCT (Carl Zeiss Meditec, USA) can scan resolutions up to 10 microns. The Stratus TD-OCT also called OCT 3 has been implemented in many clinicial studies including the RISE/RIDE and CATT studies.
Spectral domain optical coherence tomography (SD-OCT), also referred to as high definition (HD-OCT) and Fourier domain OCT became commerically available in 2006. The instrument acquires all information in a single axial scan through the tissue simultaneously by evaluating the frequency spectrum of the interference between the reflected light and a stationary reference mirror. Without a moving reference mirror, SD-OCT can aquire scans up to 5 microns of resolution. Having faster scans with increase resolution can decrease motion artifacts and allow better repeatability for tracking progression.
Current SD-OCT Instruments
Cirrus HD-OCT (Carl Zeiss Meditec, Inc, Dublin, California)
Spectralis SD-OCT (Heidelberg Engineering GmbH, Heidelberg, Germany)
RTVue (Optovue, Inc, Fremont, California)
SOCT Copernicus HR (Optopol Technology, SA, Zawiercie, Poland)
3D-OCT 1000/200 (Topcon Medical Systems, Inc, Paramus, New Jersey)
Biopitgen Envisu SD-OCT (Bioptigen, Inc, Research Triangle Park, North Carolina)
Each instrument has unique features and software that allow not only circular retinal nerve fiber layer (RNFL) scans, line scans and macular cube/volume scans but also eye tracking, optic disc parameters, deviation map, enhanced depth imaging and anterior segment capabilities.