Ophthalmic imaging by spectral optical coherence tomography

Abstract

Purpose: To demonstrate two novel ophthalmic imaging techniques based on fast Spectral Optical Coherence Tomography (SOCT).

Design: Prospective observation case report.

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.