Optical Coherence Tomography (OCT) is a standard diagnostic and imaging technique in most clinical practices today. It is a fast and noninvasive scan of the macula. By imaging the retinal histological structure, an OCT scan obtains information similar to that from an optical biopsy, but without the need for excision and histopathologic specimen processing. The OCT employs the Michelson interferometry using near-infrared light (820 nm) produced by a super luminescent diode. The light is split, and the machine compares the echo time delay of the light reflected from the retina with the echo time delay of the same light reflected from a reference mirror at a known distance.
The reflected light is recombined, and the resulting interference fringe is detected and measured by a photodiode detector. The information obtained is then used to produce an image of the retina.
Patients can expect a brief, comfortable experience with the OCT. Each scan acquisition usually takes slightly more than one second, and the entire test lasts only five to seven minutes.
The images can also be used to help patients understand their condition. The images give patients a clearer idea of what is going on in their eyes, and can better appreciate the effects of therapy.
The findings of Fourier domain OCTS are objective and quantitative, and are reproducible, making documentation much more reliable.