Rapid laser scanning produces high resolution 3-D images of living
9 May 2007
Researchers at the Massachusetts Institute of Technology
(MIT) have produced a new laser that can scan the living eye at record
speeds and produce a 3-D image of the retina in less than a second.
retinal imaging is performed with an emerging method called optical
coherence tomography (OCT), which uses light to obtain high-resolution
images of the eye, even for structures such as the retina that lie beneath
the surface. The retina converts light to electrical signals that travel to
|3-D cut-away view
of a human retina in vivo obtained with new high-speed scanning
technique. Photo credit: MIT/Ludwig-Maximilians-University
Conventional OCT imaging typically yields a series of two-dimensional
cross sectional images of the retina, which can be combined to form a 3-D
image of its volume. Even more helpful for diagnosing disease would be to
obtain very-high-resolution three-dimensional views of the eye. Limited
imaging speeds and involuntary eye motion (such as blinking) make it
difficult to perform 3-D imaging of the retinal volume.
applications, OCT systems work by scanning light back and forth across the
eye, tracing thin, micrometer-scale lines that row by row build up
high-resolution images. Commercial systems scan the eye at rates ranging
from several hundred to several thousand lines per second. A typical patient
can only keep the eye still for about one second, limiting the amount of
three-dimensional data that can be acquired.
Robert Huber (now at the
Ludwig Maximilians University in Germany) and colleagues at the MIT have
reported retinal scans at record speeds of up to 236,000 lines per second, a
factor of 10 improvement over current OCT technology. With their technique,
which uses a frequency-tunable laser to achieve fast scan speeds, they
obtained a 3-D retinal image consisting of 512x512x400 volume elements of
data in a human subject in just 0.87 seconds.
Future clinical studies, as
well as further development, may someday enable ophthalmologists to
routinely obtain three-dimensional "OCT snapshots" of the eye, containing
comprehensive volumetric information about the microstructure of the retina.
Such snapshots could potentially improve diagnoses of retinal diseases such
as diabetic retinopathy, glaucoma and age-related macular degeneration.
This research will be presented at CLEO/QELS in Baltimore, on
10 May. Meeting Paper: CThAA5, "Fourier Domain Mode Locking (FDML) in the
Non-Zero Dispersion Regime: A Laser for Ultrahigh-Speed Retinal OCT Imaging
at 236kHz Line Rate," Huber et al., Thursday, May 10, 3:45 p.m. - 4:15 p.m.