CALIFORNIA RETINA ADOPTS IMPROVED SCREENING TECHNOLOGY
Optical coherence tomography (OCT), is a technology that has become an invaluable part of ophthalmic practices because it allows doctors to see the interior of the retina in a non-invasive and non-contact fashion.
OCT performs cross-sectional or tomography imaging in the eye. The scan is analogous to ultrasound or radar, except that light is used rather than sound or radio waves to transmit data.
The first-generation OCT remains the gold standard, but recent transformations look
promising. Newer generations of OCT are incorporating spectral domain
technology in contrast to the older, time-sensitive domain
technology. For doctors, this means higher image
resolution and faster acquisition time. For patients, it
means more informed results within a shorter period of
time.
First-generation time domain OCT uses a moving mirror based interferometer to generate images. This reference mirror has to move back and forth with sequential scans. Because it depends on this mechanical moving part to perform its scans, time domain is a slower imaging modality. Because patient eye motion is occurring simultaneously, it is not feasible to use time domain OCT if precise mapping of the retinal tissue is required.
In contrast, in spectral domain OCT, the reference arm
does not move. Instead, when the light is reflected back,
the entire signal (at all wavelengths) is recorded in parallel
by a spectrometer. Because all of the echoes are
measured simultaneously as opposed to sequentially
with the reference mirror, the process is 50 to 100
times faster than time domain OCT. The scan speed of
the time domain OCT is 400 A-scan/sec, compared to
the 29,000 A-Scan/sec of a spectral domain OCT.
When the speed of OCT is increased, motion artifacts
are reduced and digital processing is not required to
align adjacent scans, resulting in more accurate retina
scans.
Given the advantages of spectral domain OCT, California Retina Consultants has upgraded to this imaging technique in many offices.