Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography

Chen, Lu; Lee, ByungKun; Schottenhamml, Julia; Maier, Andreas; Pugh, Edward N.; Fujimoto, James G.

doi:10.1167/iovs.17-22171

Cited by 66 publications

(80 citation statements)

References 41 publications

(51 reference statements)

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“…This observed elongation of foveal/parafoveal cones, and the dependence of elongation on stimulus intensity, is qualitatively consistent with previously reported elongation of peripheral cones using full-field OCT with computational aberration correction [5]. We hypothesize that the mechanism of this elongation is osmotic swelling of the outer segment, as it is consistent with observations made using conventional OCT images in human rods [4] and mouse rods, in which elongation is suppressed in mice lacking transducin [17]. In addition to OS elongation, changes in the axial morphology of cones were observed subsequent to the stimulus flash.…”

Section: Resultssupporting

confidence: 91%

“…exams, are effective after extensive pathological changes, but not in the earliest stages of disease. Adaptive optics (AO) flood imaging [1], conventional optical coherence tomography (OCT) [2,3,4], and full-field OCT [5] have revealed changes in the human photoreceptor outer segment (OS) in response to visible stimuli. Here, we describe an OCT imaging system that leverages the three-dimensional cellular resolution of AO and OCT [6,7] and the speed of a Fourier-domain mode-locked (FDML) laser [8,9].…”

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confidence: 99%

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Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

Azimipour

Migacz

Zawadzki

et al. 2018

Preprint

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Objective optical assessment of photoreceptor function may permit earlier diagnosis of retinal disease than current methods such as perimetry, electrophysiology, and clinical imaging. In this work, we describe an adaptive optics (AO) optical coherence tomography (OCT) system designed to measure functional responses of single cones to visible stimuli. The OCT subsystem consisted of a raster-scanning Fourier-domain mode-locked laser that acquires A-scans at 1.64M Hz with a center wavelength of 1063nm, and an AO subsystem providing diffraction-limited imaging. Analysis of serial volumetric images revealed phase changes of cone photoreceptors consistent with outer segment elongation and proportional to stimulus intensity, as well as other morphological changes in the outer segment and retinal pigment epithelium.

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Section: Resultssupporting

confidence: 91%

mentioning

confidence: 99%

Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

Azimipour

Migacz

Zawadzki

et al. 2018

Preprint

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“…Recent investigations in mice and humans with OCT have shown that ROS and/or cone OS elongate in response to stimuli that bleach substantial fractions of their rhodopsin. [42][43][44][45] In mouse rods, this elongation has been established to be driven by phototransduction because it requires expression of the rod Gprotein transducin. 42 Given the capability of OCT to measure submicrometer ROS length changes after suitable averaging and analysis, 42 we undertook an investigation to determine whether OCT could also be used to measure diurnal ROS length changes arising from disc shedding and renewal.…”

mentioning

confidence: 99%

“…47 The term has been recently adopted by other investigators 48 (Pandiyan et al; IOVS 2019;60; ARVO E-Abstract 1426) for the paradigm of using NIR OCT to measure bleaching-induced backscattering and/or elongation changes in the eye in vivo noninvasively. [42][43][44][45]49 We think the term deserves general adoption in vision and ophthalmology, as ORG draws an instructive parallel to the ERG, which has long been used to assess retinal function in vivo. Specifically, the ORG, like the ERG, comprises multiple components arising from distinct cells and mechanisms.…”

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confidence: 99%

Measurement of Diurnal Variation in Rod Outer Segment Length In Vivo in Mice With the OCT Optoretinogram

Zhang

Shibata

Peinado

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To investigate diurnal variation in the length of mouse rod outer segments in vivo. METHODS. The lengths of rod inner and outer segments (RIS, ROS) of dark-adapted albino mice maintained on a 12-hour dark:12-hour light cycle with light onset 7 AM were measured at prescribed times (6:30 AM, 11 AM, 3:30 PM) during the diurnal cycle with optical coherence tomography (OCT), taking advantage of increased visibility, after a brief bleaching exposure, of the bands corresponding to RIS/ROS boundaries and ROS tips (ROST). RESULTS. Deconvolution of OCT depth profiles resolved two backscatter bands located 7.4 ± 0.1 and 10.8 ± 0.2 μm (mean ± SEM) proximal to Bruch's membrane (BrM). These bands were identified with histology as arising from the apical surface of RPE and ROST, respectively. The average length of dark-adapted ROS at 6:30 AM was 17.7 ± 0.8 μm. By 11 AM, the average ROS length had decreased by 10% to 15.9 ± 0.7 μm. After 11 AM, the ROS length increased steadily at an average rate of 0.12 μm/h, returning to baseline length by 23.5 hours in the cycle. CONCLUSIONS. The diurnal variation in ROS length measured in these experiments is consistent with prior histological investigations showing that rodent rod discs are phagocytosed by the RPE maximally over several hours around the time of normal light onset. The rate of recovery of ROS to baseline length before normal light onset is consistent with the hypothesis that disc membrane synthesis is fairly constant over the diurnal cycle.

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“…For example, implementation of APM-AO-OCT should lead to broader application of OCT to brain structural imaging 60,61 where the presence of speckle in images remains a major obstacle. Finally, thanks to the improvement in the visualization of subcellular structure, APM-AO-OCT should enable a more precise localization and quantification of retinal optophysiological signals, which provide non-invasive, label-free measurement of photoreceptor function [62][63][64]…”

Section: Future Directionsmentioning

confidence: 99%

Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography

Zhang

Manna

Miller

et al. 2018

Preprint

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Speckle is an inevitable consequence of the use of coherent light in optical coherence tomography (OCT), and often acts as noise that obscures micro-structures of biological tissue. We here present a novel method of suppressing speckle noise intrinsically compatible with adaptive optics (AO) in OCT system: by modulating the phase inside the imaging system pupil aperture with a segmented deformable mirror, thus producing minor perturbations in the point spread function (PSF) to create un-correlated speckle pattern between B-scans, and further averaging to wash out the speckle but maintain the structures. It is a well-controlled and universal method which can efficiently determine the optimal range of phase modulation that minimizing speckle noise while maximizing image resolution and signal strength for different systems and/or samples. As an active method, its effectiveness and efficiency were demonstrated by both ex-vivo non-biological and in-vivo biological applications. Introduction:Speckle is a long-standing issue in all imaging technologies that use coherent light sources 1-4 , arised from the interference between light scattered by a random distributed scatters inside the system point-spread function (PSF), and observed as voxel-to-voxel intensity fluctuations in the image 5, 6 . Although speckle is a potential useful information about the dynamics of sample microstructure, in most applications it acts as a major noise source that degrades image quality. Optical coherence tomography (OCT) is a volumetric imaging technology developed in 1991 7 . It has been soon adopted in many biomedical applications 8-12 . However, as a method dependent on the coherent properties of light, OCT images suffer from speckle noise [13][14][15] .Many approaches have been taken to suppress speckle, including generation of multiple images by various means with uncorrelated speckle patterns, followed by averaging [16][17][18][19] . A weakness of these methods is that the number of uncorrelated speckle patterns that can be created is typically small, limiting speckle suppression by averaging. Speckle reduction methods using digital post-processing have also been proposed 20-23 . However, digital post-processing usually reduces speckle by spatial averaging or filtering, which necessarily reduces image resolution. Recently, it was shown that simple averaging of suitably numerous, well aligned images can reduce speckle for in vivo imaging, and it was hypothesized that subcellular motility Fig. 1 | System setup (photo in SI: Fig. S2) and the geometry of the segmented deformable mirror. a, OCT sample arm (Inset: (i) -Photo of the DM; (ii) -setup for USAF 1951 resolution test target; (iii)covariance analysis of the random segments pistons). b, Mirror configuration -Flat. c, Mirror Configuration -mirror segments with random displacements [SI: Video_S1]. d, Histogram of the mirror displacements for 100 mirror configurations in which the displacement range was 1m (0  0.5 m); Abbreviations: L#: Lens, VL: variable focus length liquid lens, ...

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Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography

Cited by 66 publications

References 41 publications

Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

Measurement of Diurnal Variation in Rod Outer Segment Length In Vivo in Mice With the OCT Optoretinogram

Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography

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