April 27, 2004.
By Emma Hitt, PhD.,
Ultra-high speed spectral domain optical coherence tomography (SD-OCT) allows imaging of large areas of the retina and rapid three-dimensional volume rendering of optic nerve head and fovea, according to a new report.
Johannes F. de Boer, PhD, from the Department of Dermatology at Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues reported their findings at the Association for Research in Vision and Ophthalmology annual meeting in Fort Lauderdale, Florida.
According to the researchers, current OCT clinical instruments are limited by acquisition speed, which takes 1.28 seconds per image, and this prevents the comprehensive screening of large retinal areas.
In the current report, the researchers suggest that the new technology is 72 times faster and has a "1.5 - 3-fold better axial resolution than current clinical instruments at the same retinal light exposure (600 µW) without compromising signal to noise."
OCT images were acquired at video rate (29 frames per second and 1,000 depth profiles per frame) with 2.5 to 6 µm axial resolution. The researchers also note that artifacts due to subject motion were significantly reduced, and this allowed mapping of structural tomography and true retinal topography.
Furthermore, Doppler OCT allowed detection of pulsatile retinal flow in arteries and veins, quantitative determination of the cardiac cycle, and flow determination in retinal capillaries.
"This advance in OCT technology will have significant impact, since accurate knowledge of retinal structure and blood flow dynamics is important in not only the treatment but also understanding the pathophysiology of many diseases, including glaucoma," the authors predict.
According to Dr. de Boer, the new technology is a far more efficient method than standard procedures. "It doesn't throw away photons. So every single photon that is reflected from the retina is detected," Dr. de Boer told Medscape. "In this way, efficiency is increased by a factor of 150, and we can increase the imaging speed without decreasing the quality of the image."
He also pointed out that the range of applications for SD-OCT is wide. "These advances we have obtained for the eye can be used for imaging other body parts, including the gastrointestinal tract and coronary arteries," he said.
"This technology represents a transition from two-dimensional imaging to three-dimensional screening of large retinal volumes," Dr. de Boer noted, "and I think the breakthrough in the efficiency allows rapid 3-D imaging for the first time."
The study was independently funded. The authors reported having a patent application on the technology.
ARVO 2004 Annual Meeting: Abstract 1139. Presented April 26, 2004.
Reviewed by Gary D. Vogin, MD.
End of article.
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