Ophthalmic imaging by spectral optical coherence tomography.

PURPOSE To demonstrate two novel ophthalmic imaging techniques based on fast Spectral Optical Coherence Tomography (SOCT). DESIGN Prospective observation case report. METHODS SETTING Research laboratory. STUDY POPULATION A normal human subject. MAIN OUTCOME MEASURES Correlation of an optical coherence retinal tomogram with known retinal anatomy, reduction of eye exposure to the probing light beam during Optical Coherence Tomography (OCT) examination. RESULTS High resolution (3- x 20-microm) cross-sectional 2-dimensional images of the human retina in vivo have been obtained with only 0.1-second total illumination time (for 1024 A-scans), and approximately 200- microW eye exposure. Details of the optic disk in vivo have been visualized at a rate of eight frames per second, which is sufficient to provide real time analysis. The 3-dimensional images of the optic nerve correspond to the images obtained from a fundus camera. CONCLUSIONS Because of its short acquisition time and high sensitivity, SOCT uses a 100 times lower exposure/A-scan to obtain images of comparable quality to those obtained by the commercial instrument based on traditional time-domain OCT. Spectral Optical Coherence Tomography therefore provides a much wider safety margin than the traditional method and allows relaxation of the current safety precautions forbidding more than 10 minutes/day scanning of the same location of a retina. As a result of the high speed offered by the new technique, the 3-dimensional tomograms, which allow a surgeon access to a comprehensive and detailed view of relevant pathologies, are obtained in a much shorter, clinically more reasonable time.