This paper presents a successful combination of ultra-high speed (120,000 depth scans/s), ultra-high resolution optical coherence tomography with adaptive optics and an achromatizing lens for compensation of monochromatic and longitudinal chromatic ocular aberrations, respectively, allowing for non-invasive volumetric imaging in normal and pathologic human retinas at cellular resolution. The capability of this imaging system is demonstrated here through preliminary studies by probing cellular intraretinal structures that have not been accessible so far with in vivo, non-invasive, label-free imaging techniques, including pigment epithelial cells, micro-vasculature of the choriocapillaris, single nerve fibre bundles and collagenous plates of the lamina cribrosa in the optic nerve head. In addition, the volumetric extent of cone loss in two colour-blinds could be quantified for the first time. This novel technique provides opportunities to enhance the understanding of retinal pathogenesis and early diagnosis of retinal diseases.
We present an ocular adaptive optics system with a wavefront sampling rate of 240 Hz and maximum recorded closed-loop bandwidth close to 25 Hz, but with typical performances around 10 Hz. The measured bandwidth depended on the specific system configuration and the particular subject tested. An analysis of the system performance as a function of achieved bandwidth showed consistently higher Strehl ratios for higher closed-loop bandwidths. This may be attributed to a combination of limitations on the available technology and the dynamics of ocular aberrations. We observed dynamic behaviour with a maximum frequency content around 30 Hz.
: Recent substantial developments in light source and detector technology have initiated a paradigm shift in retinal optical coherence tomography (OCT) performance. Broad bandwidth light sources in the 800 nm and 1060 nm wavelength region enable axial OCT resolutions of 2-3 mum and 5-7 mum, respectively. Novel high speed silicon based CMOS cameras at 800 nm and InGaAs based CCD cameras in combination with frequency domain OCT technology enable data acquisition speeds of up to 47,000 A-scans/s at 1060 nm and up to 312,500 A-scans/s at 800 nm. Combining ultrahigh axial resolution, ultrahigh speed OCT at 800 nm with pancorrected adaptive optics allows volumetric in vivo cellular resolution retinal imaging. Commercially available three-dimensional (3D) retinal OCT at 800 nm (20,000 A-scans/s, 6 mum axial resolution) is compared to ultrahigh speed 3D retinal imaging at 800 nm (160,000 A-scans/s, 2-3 mum axial resolution), high speed 3D choroidal imaging at 1060 nm (47,000 Ascan/ second, 6-7 mum axial resolution) and cellular resolution retinal imaging at 800 nm using adaptive optics OCT at 160,000 A-scans/second with isotropic resolution of ~2 mum. Analysis of the performance of these four imaging modalities applied in normal and pathologic eyes focusing on motion artifact free volumetric retinal imaging and revealing novel, complementary morphological information due to enhanced resolution, speed and penetration is presented.
This is the unspecified version of the paper.This version of the publication may differ from the final published version. In this paper we present a curvature wavefront sensor for the eye. The layout proposed is novel, whilst the algorithm used has been adapted from previously published work [1]. The design of the set-up incorporates two field lenses that, together with a beam separator, define the distance ∆z between the two defocused planes. We present a feasibility study to use this particular combination of optical configuration and retrieval algorithm in the eye. We present calibration curves and results from three real eyes. Permanent
Two high speed systems for spectrometer based frequency domain optical coherence tomography are presented. A device operating at 800 nm, based on the Basler Sprint CMOS camera with linerates of up to 312,000 lps and a device based on the Goodrich SUI LHD 1024 px camera at 1060 nm with 47,000 lps are applied in a clinical environment to normal subjects. The feasibility of clinical high and ultrahigh-resolution optical coherence tomography (OCT) devices for retinal imaging at different wavelengths, capable of isotropic sampling with 70 to 600 frames per second at 512 depth scans/frame for widefield imaging and high density sampling at 1 Gvoxel are demostrated.
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