Optical Coherence Tomography Provides High-resolution, 3D Images of the Eye

By conducting research that could improve diagnoses of many eye diseases, investigators have developed a new type of laser for taking high-resolution, three-dimensional (3D) images of the retina, the region of the eye that converts light to electrical signals that travel to the brain.

The study, performed by researchers from the Massachusetts Institute of Technology (MIT; Cambridge, MA, USA), were presented at the Conference on Lasers and Electro-Optics and the Quantum Electronics and Laser Science Conference in Baltimore, MD, USA, on May 10, 2007.

The new imaging system is based on optical coherence tomography (OCT), which uses light to obtain high-resolution, cross-sectional images of the eye to visualize slight changes that occur in retinal disease. OCT was developed in the early 1990s by MIT professor Dr. James Fujimoto, Dr. Eric Swanson at MIT Lincoln Laboratory and collaborators; Dr. Fujimoto is an author of the study.

Conventional OCT imaging characteristically yields a series of two-dimensional cross-sectional images of the retina, which can be combined to form a 3D image of its volume. The system functions by scanning light back and forth across the eye, measuring the echo time delay of reflected light along micrometer-scale lines that, row by row, build up high-resolution images.

Commercial OCT systems scan the eye at rates ranging from several hundred to several thousand lines per second. But a typical patient can only keep the eye still for about one second, limiting the amount of 3D data that can be acquired. Now, using the new laser, researchers in Dr. Fujimoto's group reported retinal scans at record speeds of up to 236,000 lines per second, a factor-of-10 improvement over current OCT technology.

Future clinical studies, as well as additional development, may someday enable ophthalmologists to routinely obtain three-dimensional "OCT snapshots” of the eye, containing comprehensive volumetric data 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.


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