Abstract
Abstract: :
Purpose: The effectiveness of image stabilization with a tracking optical coherence tomography system (TOCT) was demonstrated in human subjects. Methods: A retinal tracker was incorporated into a commercial clinical optical coherence tomography system manufactured by Carl Zeiss Meditec Inc. (CZMI). The instrument uses a secondary sensing beam in a confocal reflectometer and steering mirrors to compensate eye motion with a closed loop bandwidth of 1 kHz. The system was tested in a full clinical protocol on subjects with normal and glaucomatous eyes. The clinical protocol included peripapillary circular, peripapillary radial, and macular radial scans. Custom analysis software was developed to co–align and co–add multiple fundus and OCT images and to extract quantitative information on location of structures in the images. Results: Robust, continuous, repeatable, and clinically useful tracking on the lamina cribrosa was achieved in 96% of subjects tested in the clinical protocol. Examination of co–added peripapillary circular OCT images found an improvement in 100% and 94% of the images for normal and glaucoma subjects. Analysis of the mean variation in disc edge position found an improvement in every subject. The variation in individual sets found an improvement in 82% and 77% of intra–visit sets and a reduction in standard deviation from greater than 2 to approximately 1 pixel for normal and glaucoma subjects. Similar analysis found an improvement in 93% and 94% of individual inter–visit sets and a variance reduction from nearly 3 to approximately 1 pixel for normal and glaucoma subjects. Conclusions: TOCT achieves highly accurate OCT scan registration yielding co–added images averaged over multiple visits with well–defined boundaries and sharp fine structure. The capability to reproducibly map three–dimensional structures in the living eye at high resolution will lead to improved understanding of disease processes and improved sensitivity and specificity of diagnostic procedures.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • eye movements • imaging/image analysis: clinical