Abstract
A retinal imaging system was designed for full-field (FF) swept-source (SS) optical coherence tomography (OCT) with cellular resolution. The system incorporates a real-time adaptive optics (AO) subsystem and a very high-speed CMOS sensor, and is capable of acquiring volumetric images of the retina at rates up to 1 kHz. While digital aberration correction (DAC) is an attractive potential alternative to AO, it has not yet been shown to provide resolution allowing visualization of cones in the fovea, where early detection of functional deficits is most critical. Here we demonstrate that FF-SS-OCT with hardware AO permits resolution of foveal cones, imaged at eccentricities of 1° and 2°, with volume rates adequate to measure light-evoked changes in photoreceptors. With the reference arm blocked, the system can operate as a kilohertz AO flood illumination fundus camera with adjustable temporal coherence and is expected to allow measurement of light-evoked changes caused by common path interference in photoreceptor outer segments (OS). In this paper, we describe the system's optical design, characterize its performance, and demonstrate its ability to produce images of the human photoreceptor mosaic.
Highlights
Adaptive optics (AO) has transformed the capabilities of everyday clinical retinal imaging modalities such as flood illumination (FI) fundus camera, scanning light ophthalmoscopy (SLO), and optical coherence tomography (OCT), by permitting correction of optical aberrations introduced by the eye
Some have demonstrated that the phase of the OCT signal can be used to estimate and correct blur caused by optical aberrations [1, 24], which is especially valuable in FF-SS-OCT where optical aberrations do not affect the number of photons detected since pinholes are not used in this imaging modality [16]
We describe a FF-SS-OCT system equipped with a hardware AO subsystem designed to provide cellular resolution imaging throughout the living human retina
Summary
Adaptive optics (AO) has transformed the capabilities of everyday clinical retinal imaging modalities such as flood illumination (FI) fundus camera, scanning light ophthalmoscopy (SLO), and optical coherence tomography (OCT), by permitting correction of optical aberrations introduced by the eye. Some have demonstrated that the phase of the OCT signal can be used to estimate and correct blur caused by optical aberrations [1, 24], which is especially valuable in FF-SS-OCT where optical aberrations do not affect the number of photons detected since pinholes are not used in this imaging modality [16] This approach, termed computational adaptive optics or digital aberration correction (DAC), has been used to improve the visibility of peripheral cone photoreceptors, but has not yet been shown to resolve the smaller and more tightly packed foveal cones, whose visualization in the near-infrared (NIR) requires diffraction-limited imaging through a ∼ 7 mm pupil. Sufficiently the oscillations due to rapid light-evoked deformation of the photoreceptor outer segment (OS) [5, 17], especially the recently reported initial rapid contractile phase [29, 40]
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