1. Spectral-domain OCT (SD-OCT): Spectral-domain OCT uses 20000 u2013 70000 A-scans per second to minimize artefacts. This increases the image resolution up to 3u00b5m. It uses a spectral interference pattern between reference beams and sample beams.
These are simultaneously obtained by a spectrometer and array detector. This technique allows for faster image acquisition and results in higher quality images.
One advantage of the spectral domain OCT is the High-resolution images that it produces. A Disadvantage of the Spectral-domain OCT is Poor retinal penetrance.
2. Swept-source OCT (SS-OCT): SS-OCT is a more modified, depth-resolved technology. It was recently released to allow for control of imaging depth, higher pathology detection efficiency, longer image range and improved penetrance of the choroid.
However, the deeper penetrance trades off with a lower resolution. SS-OCT uses a narrow band of light swept through a wide range of frequencies.
Advantages: Deeper penetrance, better choroid visualization, wider image range. Disadvantages: Less resolution (transverse resolution 20u00b5m).