Adaptive optics optical coherence tomography (AO-OCT) systems capable of 3D high resolution imaging have been applied to posterior eye imaging in order to resolve the fine morphological features in the retina. Human cone photoreceptors have been extensively imaged and studied for the investigation of retinal degeneration resulting in photoreceptor cell death. However, there are still limitations of conventional approaches to AO in the clinic, such as relatively small field-of-view (FOV) and the complexities in system design and operation.
In this research, a recently developed phase-resolved Sensorless AO Swept Source based OCT (SAO-SS-OCT) system which is compact in size and easy to operate is presented. Owing to its lens-based system design, wide-field imaging can be performed up to 6° on the retina. A phase stabilization unit was integrated with the OCT system. With the phase stabilized OCT signal, we constructed retinal micro-vasculature image using a phase variance technique. The retinal vasculature image was used to align and average multiple OCT volumes acquired sequentially. The contrast-enhanced photoreceptor projection image was then extracted from the averaged volume, and analyzed based on its morphological features through a novel photoreceptor structure evaluation algorithm.
The retinas of twelve human research subjects (10 normal and 2 pathological cases) were measured in vivo. Quantitative parameters used for evaluating the cone photoreceptor mosaic such as cell density, cell area, and mosaic regularity are presented and discussed. The SAO-SS-OCT system and the proposed photoreceptor evaluation method has significant potential to reveal early stage retinal diseases associated with retinal degeneration.
Myeong Jin Ju, Morgan Heisler, Robert J. Zawadzki, Stefano Bonora, Yifan Jian, and Marinko V. Sarunic, "Wide-field human photoreceptor morphological analysis using phase-resolved sensorless adaptive optics swept-source OCT (Conference Presentation)," Proc. SPIE 10045, Ophthalmic Technologies XXVII, 1004513 (Presented at SPIE BiOS: January 29, 2017; Published: 16 May 2017); https://doi.org/10.1117/12.2253352.5370275060001.
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