BACKGROUND: Researchers at the New York Eye and Ear Infirmary have developed a new diagnostic imaging device for the eye that combines two techniques -- known as optical coherence tomography and scanning laser ophthalmoscopy -- to detect and precisely locate hard-to-spot problems in the retina, particularly macular degeneration, a major cause of blindness in the United States. Early diagnosis allows these problems to be treated in their earliest stages. A commercial version of the OCT-SLO device is now available for patients at various locations around the country. The researchers are now using OCT-SLO in combination with electroretinography to measure electrical response in the retina.
HOW IT WORKS: OCT-SLO not only painlessly produces very high resolution images of the retina in just a few minutes; it also provides a way to precisely localize aberrant blood vessels which cause the disease so treatments can be localized and better monitored. Both OCT and SLO have been available separately for years, and both involve back-scattered photons (particles of light) to produce images.
ABOUT THE RETINA: We can see because light reflects off objects in our surroundings and enters the eye through the pupil. The light is then focused and inverted by the cornea and the lens, and projected onto the back of the eye. There we find the retina, which is lined with a series of photoreceptors that convert the light signal into a neural signal. Ganglion cells then transmit those signals to the brain via the optic nerve.
BENEFITS: First developed at the Massachusetts Institute of Technology, in Cambridge, in 1991, OCT allows physicians to image and analyze tissue onsite at the time of surgery, without the need to send tissue samples to the lab, having to wait until the surgery is over for results. This in turn could lead to the need for repeat surgery. Its first clinical application was in optometry, to optically analyze the retina and cornea. The technique can also be used to image the lymph nodes to check for the spread of breast cancer. Ultimately, OCT could replace needle biopsies altogether.