Adaptive optics scanning laser ophthalmoscope with integrated wide-field retinal imaging and tracking

Abstract

We have developed a new, unified implementation of the adaptive optics scanning laser ophthalmoscope (AOSLO) incorporating a wide-field line-scanning ophthalmoscope (LSO) and a closed-loop optical retinal tracker. AOSLO raster scans are deflected by the integrated tracking mirrors so that direct AOSLO stabilization is automatic during tracking. The wide-field imager and large-spherical-mirror optical interface design, as well as a large-stroke deformable mirror (DM), enable the AOSLO image field to be corrected at any retinal coordinates of interest in a field of >25 deg. AO performance was assessed by imaging individuals with a range of refractive errors. In most subjects, image contrast was measurable at spatial frequencies close to the diffraction limit. Closed-loop optical (hardware) tracking performance was assessed by comparing sequential image series with and without stabilization. Though usually better than 10 μm rms, or 0.03 deg, tracking does not yet stabilize to single cone precision but significantly improves average image quality and increases the number of frames that can be successfully aligned by software-based post-processing methods. The new optical interface allows the high-resolution imaging field to be placed anywhere within the wide field without requiring the subject to re-fixate, enabling easier retinal navigation and faster, more efficient AOSLO montage capture and stitching.

In vivo adaptive optics microvascular imaging in diabetic patients without clinically severe diabetic retinopathy

“…In addition, each subject had measurement of axial lengths using the IOL Master (Carl Zeiss Meditec, Carlsbad, CA). AOSLO imaging was performed using the Indiana AOSLO [43]. This system uses a woofer tweeter wavefront control system [44,45] to provide en face, high-resolution images of retinal structures, with the capability of focusing on superficial or deeper retinal layers.…”

Superimposed multi-resolution imaging

“…Multi-channel imaging with multiple resolutions or even employing multiple imaging modalities has been implemented for added functionality in specialized applications such as in microscopy [14], skin surface imaging [15], laparoscopic surgery [8], or ophthalmoscopy [16,17]. An intermediate stage of this approach is to segment the detector into two or more channels of varying resolution [10].…”

Combined high contrast and wide field of view in the scanning laser ophthalmoscope through dual detection of light paths

“…8,10,11,13,[17][18][19][20] Several researchers have reported on the benefit provided by the use of different pinhole apertures as spatial filters, 13,[17][18][19][21][22][23] including multichannel imaging, 20,23,24 however, confocal imaging with small pinholes is limited to relatively small fields of view of <30 deg or an order-of-magnitude less than this for diffraction-limited imaging achievable with adaptive-optics correction. [25][26][27][28] The effect of optical aberrations on the image of the retina is much more severe than for the illuminating beam since image formation uses the whole pupil, so the numerical aperture for the imaging return path is typically 10 times greater than for the illuminating beam yielding commensurately higher levels of aberration. Consequently for field angles greater than about 30 deg, the effective imaging PSF, including the effects of an extended retinal-tissue PSF, exceeds the dimensions of the imaged pinhole preventing confocal operation.…”