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Inner Retinal Changes in Primary Open-Angle Glaucoma Revealed Through Adaptive Optics-Optical Coherence Tomography
摘要： To examine the microstructural changes in the inner nuclear layer (INL) and ganglion cell layer (GCL) in a primary open-angle glaucoma (POAG) subject at 2 timepoints, 4 months apart. This case-control study (1 POAG subject and 1 normal control) used the single cell, 3-dimensional volumetric imaging capability of an adaptive optics-optical coherence tomography-scanning laser ophthalmoscopy system to examine the inner retina. At the area of greatest glaucomatous change in the POAG subject [3-degrees temporal (T), 3-degrees inferior (I), right eye], the GCL was greatly thinned at both timepoints, yet retinal ganglion cell soma remained visible amid a meshwork of capillaries. Microcystic lesions in the INL were visible at both timepoints, ranging in diameter from 8 to 43 μm on day 1 to 11 to 64 μm at 4 months, with an average diameter increase of ～124%. Small hyperre?ective features (not seen in the contralateral eye or control subject) at a depth midway through the INL seemed correlated to the development of microcysts. We demonstrate the ability to image microcystic lesions early in their development and have quanti?ed longitudinal changes. The presence of small hyperre?ective structures at a layer midway through the INL seems to be a precursor to their formation and is a potential biomarker for assessing POAG severity and progression. The adaptive optics imaging system is also able to visualize retinal ganglion cells in this subject, despite severe thinning of the GCL.
关键词： optical coherence tomography,adaptive optics,retinal ganglion cells,microcysts,primary open-angle glaucoma
更新于2025-09-16 10:30:52
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Automated Optical Flow Based Registration For Adaptive Optics Scanning Laser Ophthalmoscope
摘要： This study presents an automated registration method based on optical flow for an adaptive optics scanning laser ophthalmoscope. The method was designed to align and average images to obtain a higher signal-to-noise ratio image. A correlation based optical flow image registration method, which has large registration degrees of freedom, is adopted as a local registration method. By comparing the images before and after image registration, we show the effectiveness of our method. Furthermore, the advantage of our method, which is the containment of large registration degrees of freedom, is confirmed.
关键词： Retinal images,Image processing,Imaging systems,Optical flow,Active or adaptive optics,Ophthalmology
更新于2025-09-16 10:30:52
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Performance analysis of 349-element adaptive optics unit for a coherent free space optical communication system
摘要： As a continuation of our previous work [Optics Express.25, 15229(2017)] in which we have verified the performance of a coherent free space optical communication (FSOC) system with a 97-element adaptive optics (AO) system, in this paper, we evaluated the performance improvement of the coherent FSOC system using a large-scale high-speed AO system with a 349-element continuous surface deformable mirror. The mixing efficiency (ME) and bit-error-rate (BER) under different Greenwood frequency (GF) were calculated as the performance metric of coherent FSOC system. The performance of FSOC system using such a large-scale AO system was quantitatively verified for the first time. The obtained results showed that the performance was obviously improved when a larger-scale high-speed AO system is employed in coherent FSOC system. This analysis result provides a performance verification for large-scale high-speed AO systems used in FSOC system which is beneficial for coherent FSOC system parameters design.
关键词： bit-error-rate,adaptive optics,free space optical communication,coherent detection,mixing efficiency
更新于2025-09-11 14:15:04
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Characterization of Inner Retinal Hyperreflective Alterations in Early Cognitive Impairment on Adaptive Optics Scanning Laser Ophthalmoscopy
摘要： PURPOSE. To examine inner retinal hyperre?ective features on adaptive optics scanning laser ophthalmoscopy (AOSLO) in individuals with early cognitive impairment. METHODS. In this prospective, cross-sectional study, we enrolled 12 participants with either amnestic mild cognitive impairment (aMCI, n ? 10) or early dementia due to Alzheimer’s disease (eAD, n ? 2) and 12 age-, sex-, and race-matched cognitively normal controls. All participants completed AOSLO imaging of the peripapillary area were graded for hyperre?ective features including granular membranes, mottled membranes, and nummular features. Regions of interest on AOSLO were compared qualitatively to corresponding optical coherence tomography (OCT) cross sections. OCT was also used to analyze peripapillary retinal nerve ?ber layer (RNFL) thickness. RESULTS. Cognitively impaired individuals had a signi?cantly higher number of granular membranes with a larger overall area compared to controls. The proportion of cognitively impaired individuals with two or more granular membranes was 41.7% compared to none in the control group. Granular membrane area was also inversely correlated with cognitive performance on the Montreal Cognitive Assessment. There was no difference between the two groups in terms of other membrane types or RNFL thickness. CONCLUSIONS. Individuals with early cognitive impairment related to Alzheimer’s show hyperre?ective granular membranes on high-resolution imaging, which we hypothesize to be manifestations of inner retinal gliosis. The presence of these subtle hyperre?ective membranes may obscure underlying RNFL thinning in these eyes on OCT imaging. The distinctive phenotype of granular membranes surrounding the optic nerve on AOSLO may represent a new potential biomarker of early Alzheimer’s.
关键词： cognitive impairment,adaptive optics scanning laser ophthalmoscopy,aoslo,alzheimer’s disease,gliosis
更新于2025-09-11 14:15:04
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Optical and neural anisotropy in peripheral vision
摘要： Optical blur in the peripheral retina is known to be highly anisotropic due to nonrotationally symmetric wavefront aberrations such as astigmatism and coma. At the neural level, the visual system exhibits anisotropies in orientation sensitivity across the visual field. In the fovea, the visual system shows higher sensitivity for cardinal over diagonal orientations, which is referred to as the oblique effect. However, in the peripheral retina, the neural visual system becomes more sensitive to radially-oriented signals, a phenomenon known as the meridional effect. Here, we examined the relative contributions of optics and neural processing to the meridional effect in 10 participants at 08, 108, and 208 in the temporal retina. Optical anisotropy was quantified by measuring the eye’s habitual wavefront aberrations. Alternatively, neural anisotropy was evaluated by measuring contrast sensitivity (at 2 and 4 cyc/deg) while correcting the eye’s aberrations with an adaptive optics vision simulator, thus bypassing any optical factors. As eccentricity increased, optical and neural anisotropy increased in magnitude. The average ratio of horizontal to vertical optical MTF (at 2 and 4 cyc/deg) at 08, 108, and 208 was 0.96 6 0.14, 1.41 6 0.54 and 2.15 6 1.38, respectively. Similarly, the average ratio of horizontal to vertical contrast sensitivity with full optical correction at 08, 108, and 208 was 0.99 6 0.15, 1.28 6 0.28 and 1.75 6 0.80, respectively. These results indicate that the neural system’s orientation sensitivity coincides with habitual blur orientation. These findings support the neural origin of the meridional effect and raise important questions regarding the role of peripheral anisotropic optical quality in developing the meridional effect and emmetropization.
关键词： peripheral retina,anisotropy,wavefront aberrations,neural adaptation,adaptive optics
更新于2025-09-11 14:15:04
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Lateral resolution enhancement using programmable phase modulator in optical coherence tomography
摘要： Adaptive optics plays an important role in the correction of high-order aberrations to enhance lateral resolution. An OCT system coupled with a programmable phase modulator is designed to verify lateral resolution improvement. The Hamamatsu high-resolution, non-pixelized, optically addressed light modulator (PAL-SLM) PPM X7550 series is used to correct aberrations, utilizing a simple method based on phase information from OCT images. The advantages of this method are its high simplicity and low cost. A raster scanning technique is adopted to scan samples covered with scattering suspension. Metal lines covered with scattering suspension are imaged, and a respective correction is applied to remove the aberration. Results demonstrate an improvement in lateral resolution on metal grid samples.
关键词： lateral resolution,PAL-SLM,adaptive optics,aberration correction,OCT
更新于2025-09-11 14:15:04
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Efficient Spectroscopy of Exoplanets at Small Angular Separations with Vortex Fiber Nulling
摘要： Instrumentation designed to characterize potentially habitable planets may combine adaptive optics and high-resolution spectroscopy techniques to achieve the highest possible sensitivity to spectral signs of life. Detecting the weak signal from a planet containing biomarkers will require exquisite control of the optical wavefront to maximize the planet signal and significantly reduce unwanted starlight. We present an optical technique, known as vortex fiber nulling (VFN), that allows polychromatic light from faint planets at extremely small separations from their host stars (～λ/D) to be efficiently routed to a diffraction-limited spectrograph via a single-mode optical fiber, while light from the star is prevented from entering the spectrograph. VFN takes advantage of the spatial selectivity of a single-mode fiber to isolate the light from close-in companions in a small field of view around the star. We provide theoretical performance predictions of a conceptual design and show that VFN may be utilized to characterize planets detected by radial velocity (RV) instruments in the infrared without knowledge of the azimuthal orientation of their orbits. Using a spectral template-matching technique, we calculate an integration time of ～400, ～100, and ～30 hr for Ross 128 b with Keck, the Thirty Meter Telescope, and the Large Ultraviolet/Optical/Infrared Surveyor, respectively.
关键词： techniques: spectroscopic,instrumentation: adaptive optics,instrumentation: high angular resolution
更新于2025-09-10 09:29:36
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Repeatability of Cone Spacing Measures in Eyes With Inherited Retinal Degenerations
摘要： PURPOSE. To determine short-term variability of adaptive optics scanning laser ophthalmoscopy (AOSLO)–derived cone spacing measures in eyes with inherited retinal degenerations (IRD) and in normal eyes. METHODS. Twenty IRD patients and 10 visually normal subjects underwent AOSLO imaging at two visits separated by no more than 1 month (NCT00254605). Cone spacing was measured in multiple macular regions in each image by three independent graders. Variability of cone spacing measures between visits, between graders, and between eyes was determined and correlated with standard clinical measures. RESULTS. Cone spacing was measured in 2905 regions. Interobserver agreement was high both in normal eyes and eyes with IRD (mean intraclass correlation coef?cient [ICC] ? 0.838 for normal and 0.892 for eyes with IRD). Cone spacing measures were closely correlated between visits (ICC > 0.869 for both study groups). Mean relative intervisit spacing difference (absolute difference in measures divided by the mean at each region) was 4.0% for normal eyes and 4.9% for eyes with IRD. Cone spacing measures from fellow eyes of the same subject showed strong agreement for all subjects (ICC > 0.85 for both study groups). CONCLUSIONS. Adaptive optics scanning laser ophthalmoscopy–derived macular cone spacing measures were correlated between observers, visits, and fellow eyes of the same subject in normal eyes and in eyes with IRD. This information may help establish the role of cone spacing measures derived from images of the cone mosaic obtained with AOSLO as a sensitive biomarker for longitudinal tracking of photoreceptor loss during disease progression and in response to treatment. (ClinicalTrials.gov number, NCT00254605.)
关键词： retinal,adaptive optics,photoreceptor,imaging,retinitis pigmentosa,retinal degeneration
更新于2025-09-10 09:29:36
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Retinal Vascular Branching in Healthy and Diabetic Subjects
摘要： PURPOSE. To measure the effect of nonproliferative diabetic retinopathy (NPDR) on retinal branching. To compare vascular branching in healthy and diabetic subjects with established biophysical models. METHODS. Vascular bifurcations in arteries and veins were imaged in 17 NPDR and 26 healthy subjects with the Indiana adaptive optics scanning laser ophthalmoscope (AOSLO). Vessel measurements were grouped according to parent vessel diameters into large ((cid:2)50 ~ <100 lm) and small ((cid:2)20 ~ <50 lm) sizes. Vessel diameters and bifurcation angles were measured manually. Vascular diameters were compared with predictions of Murray’s law using curve ?tting. For analysis of bifurcation angles, two models from Zamir were compared: one based on the power required for blood pumping, the other based on drag force between blood and vascular wall. RESULTS. For normal larger vessels, the exponent relating the parent and daughter branching diameters was signi?cantly less than the value of 3 predicted by Murray’s law (arteries: 2.59; veins: 1.95). In NPDR, the best-?t exponent was close to 3 for arteries but close to 2 in healthy subjects in veins, (arteries: 3.09; veins: 2.16). For both small arteries and veins, diabetics’ exponent differed from healthy subjects (P < 0.01). Bifurcation angles in the healthy subjects (788 6 with a standard error (SE) of 0.98) were not much different than in NPDR (798 6 SE 1.38). The model based on minimizing pumping power predicted the measurements better than the one minimizing the vascular drag and lumen surface area. CONCLUSIONS. The relation between parent and daughter branch diameters changes in diabetes, but the branching angles do not.
关键词： adaptive optics scanning laser ophthalmoscopy,diabetic retinopathy,vascular branching,Murray’s law
更新于2025-09-10 09:29:36
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Numerical study of orbital angular momentum-entanglement in turbulence with adaptive optics system compensation
摘要： While the entangled orbital angular momentum (OAM) photons propagate through the turbulent atmosphere, the OAM entanglement is decoherent. Adaptive optics (AO) system is an effective technique to mitigate wavefront distortion induced by atmospheric turbulence. In this paper, we investigate the performance of the system when the entangled OAM photons propagate though atmospheric turbulence with AO system compensation. The influence of reconstruction algorithm and spatial bandwidth of corrector is analyzed. The results show that branch-point (BP) algorithm has better compensation performance when Rytov number > 0.2 than the least mean square error (LS) algorithm. High spatial bandwidth has better compensation performance.
关键词： turbulence,orbital angular momentum,compensation,adaptive optics,entanglement
更新于2025-09-10 09:29:36