Adaptive Optics Ophthalmoscopy Research Articles

Adaptive Optics Imaging in Patients Affected by Pseudoxanthoma Elasticum

To describe the retinal findings of patients affected by pseudoxanthoma elasticum (PXE) using a multimodal imaging approach including flood-illumination adaptive optics ophthalmoscopy (AO). Retrospective case series. Patients affected by PXE were retrospectively studied. Clinical data, color, infrared and autofluorescence fundus imaging, optical coherence tomographic scans, and AO examinations were collected. Furthermore, the photoreceptor count was assessed. PXE diagnosis was confirmed by a positive skin biopsy and/or genetic testing. Twenty-one eyes of 18 patients (11 females and 7 males) were included in the study. In 3 patients, both eyes were studied. The mean age at examination was 37 ± 16.4 years (range 11-66) and the mean best-corrected visual acuity (BCVA) was 0.1 ± 0.2 logMAR (range 0-1). We identified 3 types of angioid streaks (AS) using AO: "crack," "band," and "hypopigmented." The first 2 were very similar and they differed in size; the third type showed specific clinical features. Comet lesions appeared as hyper-reflective round lesions on AO imaging. In all eyes, the cone mosaic appeared reduced inside the streaks compared to the neighboring areas (13,532.8 ± 1,366.5 cones/mm2 vs 16,817.1 ± 1,263.0 cones/mm2 respectively). Using AO imaging in PXE-related retinopathy, we were able to observe the presence of the photoreceptors within the angioid streaks, differentiate 3 types of angioid streaks, based on size and reflective features, and identify the very small crystalline bodies not identifiable using other retinal imaging techniques.

Label-free imaging of immune cell dynamics in the living retina using adaptive optics.

Our recent work characterized the movement of single blood cells within the retinal vasculature (Joseph et al. 2019) using adaptive optics ophthalmoscopy. Here, we apply this technique to the context of acute inflammation and discover both infiltrating and tissue-resident immune cells to be visible without any labeling in the living mouse retina using near-infrared light alone. Intravital imaging of immune cells can be negatively impacted by surgical manipulation, exogenous dyes, transgenic manipulation and phototoxicity. These confounds are now overcome, using phase contrast and time-lapse videography to reveal the dynamic behavior of myeloid cells as they interact, extravasate and survey the mouse retina. Cellular motility and differential vascular responses were measured noninvasively and in vivo across hours to months at the same retinal location, from initiation to the resolution of inflammation. As comparable systems are already available for clinical research, this approach could be readily translated to human application.

IN VIVO OBSERVATION OF RETINAL VASCULAR DEPOSITS USING ADAPTIVE OPTICS IMAGING IN FABRY DISEASE.

To report a novel finding in patients with Fabry disease, that is, the observation by adaptive optics ophthalmoscopy of intracellular lipidic deposits in retinal vessels. Observational two-center case series. Eighteen patients with genetically proven Fabry disease underwent flood-illumination adaptive optics ophthalmoscopy imaging (rtx1; Imagine Eyes, Orsay, France) of retinal vessels. Fourteen patients (78% of all patients; 7 of the 10 women and 7 of the 8 men) showed paravascular punctuate or linear opacities in both eyes. In the least-affected patients, these were seen only in the wall of precapillary arterioles as discrete spots of 5 µm to 10 µm large, whereas in those more severely affected, capillaries and first-order vessels were also involved with diffuse opacification of the wall. These deposits sometime showed a striated pattern, suggesting colocalization with vascular smooth muscle cells. Adaptive optics ophthalmoscopy of retinal vessels may be of interest for patients with Fabry disease, providing noninvasive, gradable evaluation of microvascular involvement.

Non-invasive evaluation of retinal vascular remodeling and hypertrophy in humans: intricate effect of ageing, blood pressure and glycaemia.

Ageing, hypertension and diabetes have an intricate effect on microvascular structure. In the retina, the respective contribution of remodeling and hypertrophy in such process is still unclear. We aimed at disentangling age, blood pressure and glycaemia effects onretinal microcirculation using the non-invasive adaptive optics ophthalmoscopy (AOO). We included 429 subjects, distributed into 4 groups according to normal (nBP) or high blood pressure (hBP) and/or normal (nGly) or high fasting glycaemia (hGly). The nBP/nGly group was stratified in age tertiles to isolate theeffect of ageing. AOO was used to measure arteriolar wall thickness (WT, µm), arteriolar (aID, µm) and venular internal diameter (vID, µm) and calculate arteriolar wall-to-lumen ratio (WLR), wall cross-sectional area (WCSA, µm2). One-way ANOVA for parametric variables and Kruskal-Wallis test for non-parametric variables were used for comparison among groups. A multivariate regression analysis including age, gender, BP, hGly and antihypertensive treatment was performed to calculate independent predictors of retinal remodeling. WT was increased with ageing (tertile1: 22.5 ± 3.2, tertile2: 24.2 ± 3.5, tertile 3: 25.2 ± 3.8, p = 0.001) and BP (hBP: 25.2 ± 4.1 vs nBP: 23.9 ± 3.7, p = 0.003). aID decreased with BP (hBP: 90.2 ± 13.4 vs nBP: 93.6 ± 11.6, p = 0.013) and increased with glycaemia (hGly: 97.7 ± 12.5 vs nGly: 93.6 ± 11.6, p = 0.002). Amultivariate analysis showed independent association of hBPwithWLR; hGly withWCSA; ageing with WLR and WCSA. AOO non-invasively identifies retinal structural changes in human confirming that microvascular remodeling is exclusively related to hypertension, whereas vascular growth is related to ageing and hyperglycaemia.

ATTENUATION OUTER RETINAL BANDS ON OPTICAL COHERENCE TOMOGRAPHY FOLLOWING MACULAR EDEMA: A Possible Manifestation of Photoreceptor Misalignment.

Macular edema is a common retinal disease which may leave important anatomical and functional sequelaes. Directional fundus imaging consists of comparing on- and off-axis images to reveal angle-dependent reflectance properties of fundus structures, which may be related to misaligned photoreceptors. Here, we analyzed directional optical coherence tomography (OCT) and flood-illumination adaptive optics ophthalmoscopy images to detect evidence of misaligned photoreceptors following macular edema. Transversal, observational study. Nine patients having recovered a normal macular profile after macular edema due to retinal vein occlusion were included. For each patient, a reference OCT scan (i.e., with the incident beam normal to the fovea) was acquired, and off-axis scans were then acquired by laterally shifting the entry pupil. In addition, in four of these eyes, directional adaptive optics ophthalmoscopy documented the directional variations of cone metrics. Included patients comprised two women and seven men (age range, 19-76 years). Reference OCT scans showed patchy attenuation of the cone outer segment tips and to a lesser extent of the inner segment/outer segment lines in all, but two eyes; these. Increased intensity of the cone outer segment tips and inner segment/outer segment lines could be observed on off-axis scans. Accordingly, fusion images showed 66% average reduction of the length of cone outer segment tips attenuation. In two cases, although reference scans showed continuity of outer bands, focal attenuation was evidenced in off-axis images. Directional adaptive optics ophthalmoscopy imaging showed a strong directional variability of cone counts in these areas, ranging from near absence to roughly two-third of reference values. In each case, directional variations of cone counts paralleled those of the reflectance of outer bands. After macular edema, focal attenuations of the inner segment/outer segment and of the cone outer segment tips lines may be present on OCT. These areas may show a strong directional variability by both OCT and adaptive optics ophthalmoscopy, suggesting that misaligned photoreceptor outer segments contribute to such features. The evaluation of outer retinal damage following macular edema should therefore take into account the optical Stiles-Crawford effect to disambiguate missing from misaligned cones.

Effect of A Multinutrient Complex on Retinal Microcirculation in Diabetic Patients Investigated Using an Adaptive Optics Retinal Camera.

Alimentary supplements may have beneficial effects on retinal microvasculature in diabetic patients. State-of-the-art imaging techniques were used to assess retinal microcirculation in diabetic patients in an observational study before and after 3 months treatment with a multinutrient complex including resveratrol, vitamins D3, C, E, essential fatty acids, trace elements (zinc and copper) and macular pigments (lutein and zeaxanthin)-Resvega. Fifteen subjects were included in this study. Adaptive optics ophthalmoscopy was used to measure the parameters of temporal retinal arterioles. Optical coherence tomography angiography was employed to assess foveal avascular zone and vessel densities of the superficial capillary plexus, deep capillary plexus and choricapillary plexus. After 3 months of treatment, there was a statistically significant median decrease in wall-to-lumen ratio (p=0.0001). The same tendencies were noticed for wall thickness values (p=0.008) and wall cross sectional area values (p=0.001). On the other side, no significant changes were noticed concerning the OCTA parameters. Resvega seems to have a beneficial effect on the retinal arterioles in diabetic patients.

High resolution imaging of radiation retinopathy

AbstractWe explored by fundus photographs, OCT and adaptive optics ophthalmoscopy (AOO) the vessels of eyes after proton beam therapy for uveal melanoma in 10 eyes. We observed strong fluctuations of diameters in both arteries and veins, without significant changes in vascular wall thickness suggesting that vasoconstriction was involved in this process. Reduction of lumen diameter could be focal or diffuse, and could lead in some cases to branch retinal vein occlusion unrelated to arteriovenous crossings. The ensuing collateral circulation could lead to the development of TelCaps (capillary macroaneurysms), successfully treated by targeted laser in one case. Many areas of capillary closure followed a vascular perfusion or drainage scheme, suggesting that vasoconstriction played a role in the complex pattern of radiation retinopathy. This may provide the basis for therapeutic trials based on the modulation of vasomotricity.

High-Resolution Imaging of Retinal Vasculitis by Flood Illumination Adaptive Optics Ophthalmoscopy: A Follow-up Study

ABSTRACT Purpose: To monitor perivascular sheathing during the course of retinal vasculitis by flood illumination adaptive optics ophthalmoscopy (AOO). Methods: Perivenous sheathing and venous diameters were quantitatively analyzed by semi-automatic segmentation of AOO images in 12 eyes of treatment-naive patients with retinal vasculitis. Results: The width of venous sheathing ranged from 45 to 225 µm (mean 101.0 µm ± 54.3). In 10 cases, the underlying vein showed focal narrowing (mean ± SD 14% ± 10). Focal narrowing of arteries was also present in one eye. At presentation, width of sheathing and vessel diameters were not correlated with fluorescein leakage. During follow-up, 5 eyes showed an increase in vein diameter or resolution of narrowing and in 10 eyes a thinning of vascular sheathing was observed (p= .003). Conclusions: Perivenous sheathing may be quantitatively analyzed and monitored by AOO. AOO may therefore contribute to monitor vascular sheathing during posterior uveitis.

High-resolution imaging of diabetic retinopathy lesions using an adaptive optics retinal camera

Purpose. Adaptive optics (AO) imaging is a promising high-resolution investigation technique in ophthalmology that can bring new information about the pathophysiology of diabetic retinopathy. Material and methods. Seven patients previously diagnosed with diabetic retinopathy were investigated with optical coherence tomography (OCT) scanning, OCT angiography, fundus photo, and AO retinal camera (rtx1TM, Imagine Eyes, Orsay, France). Results. The red lesions on fundus photos appeared on AO imaging as hyporeflective lesions. OCT angiography helped us to differentiate between microaneurysms and hemorrhages. Hard exudates had a heterogeneous granular appearance. Retinal oedema was proved to have a blurring effect on the AO images. In addition to this, cystic spaces were identified to have a hyporeflective demarcation line. Conclusions. AO imaging is offering a fine documentation of retinal lesions and might become an important instrument for early diagnosis of diabetic retinopathy and for explaining its pathophysiological mechanisms. Abbreviations: AO = adaptive optics, AOO = adaptive optics ophthalmoscopy, SS = swept source, OCT =optical coherence tomography, SLO = scanning laser ophthalmoscope.

RETINAL MICROCIRCULATION INVESTIGATION IN TYPE I AND II DIABETIC PATIENTS WITHOUT RETINOPATHY USING AN ADAPTIVE OPTICS RETINAL CAMERA.

State of art imaging techniques might be a useful tool to early detect the retinal vessels lesions in diabetes. This analytical observational study investigates the retinal microcirculation changes in type I and II diabetic patients without retinopathy using adaptive optics ophthalmoscopy (AOO) and optical coherence ophthalmoscopy angiography (OCTA). Fifty-five subjects were included in this study and were divided in three groups: type I diabetic group (n=16), type II diabetic group (n=19) and control group (n=20). An adaptive optics retinal camera was used to assess the parameters of the temporal superior retinal arterioles. Moreover, vessel density of the superficial capillary plexus across the parafoveal area was measured with OCT-A. All cases were investigated once, in a cross-sectional design. Diabetic patients from both groups had a higher wall-to-lumen-ratio compared to the controls (p=0.01 and 0.01, respectively). Interestingly, no significant differences were found between the two diabetic groups (p=0.69). Moreover, the vessel density was smaller in the type I diabetic group than in the control group (p=0.001). AOO might be a useful tool to detect early retinal vascular changes in diabetes before any clinical signs and together with OCTA it might bring important information on the prognostic and pathophysiology of the disease.

Infrared autofluorescence in adaptive optics ophthalmoscopy for imaging retinal pigment epithelial cells in health and disease

Infrared autofluorescence in adaptive optics ophthalmoscopy for imaging retinal pigment epithelial cells in health and disease

Fast adaptive optics scanning light ophthalmoscope retinal montaging.

The field of view of high-resolution ophthalmoscopes that require the use of adaptive optics (AO) wavefront correction is limited by the isoplanatic patch of the eye, which varies across individual eyes and with the portion of the pupil used for illumination and/or imaging. Therefore all current AO ophthalmoscopes have small fields of view comparable to, or smaller than, the isoplanatic patch, and the resulting images have to be stitched off-line to create larger montages. These montages are currently assembled either manually, by expert human graders, or automatically, often requiring several hours per montage. This arguably limits the applicability of AO ophthalmoscopy to studies with small cohorts and moreover, prevents the ability to review a real-time captured montage of all locations during image acquisition to further direct targeted imaging. In this work, we propose stitching the images with our novel algorithm, which uses oriented fast rotated brief (ORB) descriptors, local sensitivity hashing, and by searching for a ‘good enough’ transformation, rather than the best possible, to achieve processing times of 1–2 minutes per montage of 250 images. Moreover, the proposed method produces montages which are as accurate as previous methods, when considering the image similarity metrics: normalised mutual information (NMI), and normalised cross correlation (NCC).

Adaptive optics ophthalmoscopy: Application to age-related macular degeneration and vascular diseases.

Adaptive optics (AO)-enhanced en face retinal imaging, termed here AO ophthalmoscopy (AOO) has reached a level of robustness which fuels its increasing use in research and clinical centers. Here we will review the contribution of clinical AOO to the understanding and monitoring of 1) age-related macular degeneration and 2) vascular diseases. The main contributions of AOO to the phenotyping of AMD are a better identification of drusen, a better delineation of the limits of atrophy, and the identification of novel features such as punctate hyperreflectivity and mobile melanin-containing clumps. Characterization of progression of atrophy is facilitated by time-lapse imaging. In vessels, AOO enables the observation and measurement of parietal structures and the observation of microscopic pathological features such as small hemorrhages and inflammatory cell accumulations.

Sub-Airy Confocal Adaptive Optics Scanning Ophthalmoscopy.

PurposeTo demonstrate the viability of improving transverse image resolution in reflectance scanning adaptive optics ophthalmoscopy using sub-Airy disk confocal detection.MethodsThe foveal cone mosaic was imaged in five human subjects free of known eye disease using two custom adaptive optics scanning light ophthalmoscopes (AOSLOs) in reflectance with 7.75 and 4.30 mm pupil diameters. Confocal pinholes of 0.5, 0.6, 0.8, and 1.0 Airy disk diameters (ADDs) were used in a retinal conjugate plane before the light detector. Average cone photoreceptor intensity profile width and power spectrum were calculated for the resulting images. Detected energy using a model eye was recorded for each pinhole size.ResultsThe cone photoreceptor mosaic is better resolved with decreasing confocal pinhole size, with the high spatial frequency content of the images enhanced in both the large- and small-pupil AOSLOs. The average cone intensity profile width was reduced by ∼15% with the use of a 0.5 ADD pinhole when compared to a 1.0 ADD, with an accompanying reduction in signal greater than a factor of four.ConclusionsThe use of sub-Airy disk confocal pinhole detection without increasing retinal light exposure results in a substantial improvement in image resolution at the cost of larger than predicted signal reduction.Translational RelevanceImprovement in transverse resolution using sub-Airy disk confocal detection is a practical and low-cost approach that is applicable to all point- and line-scanning ophthalmoscopes, including optical coherence tomographers.

Diagnostic imaging with ultrahigh resolution adaptive optics ophthalmoscopy

Diagnostic imaging with ultrahigh resolution adaptive optics ophthalmoscopy

In Vivo Adaptive Optics Ophthalmoscopy Correlated with Histopathologic Results in Cancer-Associated Retinopathy

To demonstrate the validity of adaptive optics scanning laser ophthalmoscopy (AOSLO) imaging of the retina in human disease based on clinicopathologic correlation in a patient with cancer-associated retinopathy (CAR). Case report. Sixty-four-year-old man with CAR. Fundus photography, electroretinography, visual field testing, fundus autofluorescent imaging, spectral-domain OCT scans, AOSLO, and histopathologic analysis were performed. Comparison of AOSLO with histopathologic results. Changes in photoreceptor morphologic features were correlated highly between AOSLO and histopathologic results. We present a unique case where a patient with a rare and fatal disease, CAR, underwent AOSLO imaging during the course of the disease, and then shortly thereafter, postmortem histopathologic analysis of the eyes was carried out. This is the first report of use of AOSLO to elucidate further the retinal changes that occur in CAR and the first study to demonstrate correlation of AOSLO with histopathologic results in any human disease.

Open source software for automatic detection of cone photoreceptors in adaptive optics ophthalmoscopy using convolutional neural networks

Imaging with an adaptive optics scanning light ophthalmoscope (AOSLO) enables direct visualization of the cone photoreceptor mosaic in the living human retina. Quantitative analysis of AOSLO images typically requires manual grading, which is time consuming, and subjective; thus, automated algorithms are highly desirable. Previously developed automated methods are often reliant on ad hoc rules that may not be transferable between different imaging modalities or retinal locations. In this work, we present a convolutional neural network (CNN) based method for cone detection that learns features of interest directly from training data. This cone-identifying algorithm was trained and validated on separate data sets of confocal and split detector AOSLO images with results showing performance that closely mimics the gold standard manual process. Further, without any need for algorithmic modifications for a specific AOSLO imaging system, our fully-automated multi-modality CNN-based cone detection method resulted in comparable results to previous automatic cone segmentation methods which utilized ad hoc rules for different applications. We have made free open-source software for the proposed method and the corresponding training and testing datasets available online.

The relationship between perifoveal achromatic, L- and M-cone acuity and retinal structure as assessed with multimodal high resolution imaging

The relationships between perifoveal measures of achromatic-, L- and M-cone acuity and retinal structure were investigated in healthy young males. Thirty-two males, aged 20–39years, with normal foveal logMAR letter acuity and no observed ocular abnormalities participated in the study. Achromatic and isolated L- and M-cone spatial acuity was measured in the dominant eye with a Sloan E letter of 90% achromatic decrement contrast or 23% increment cone contrast, respectively. Separately, the central part of the same eye was imaged with high-resolution spectral-domain optical coherence tomography (SD-OCT) and adaptive optics ophthalmoscopy (AOO). Thickness measures and cone density in the fovea and parafoveal region were not correlated with perifoveal structural measures. A significant correlation was observed between thicker retinal pigment epithelium (RPE) complex, higher cone density and better L-cone logMAR at 5deg eccentricity, but not for achromatic or M-cone logMAR. The results imply that single letter perifoveal L-cone acuity, rather than achromatic acuity, may provide a useful measure for assessing the structure-function relationship and detecting early changes in the perifoveal cone mosaic.

The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay.

Over the past 25years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed invivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come.

First-order design of a reflective viewfinder for adaptive optics ophthalmoscopy

Adaptive optics (AO) ophthalmoscopes with small fields of view have limited clinical utility. We propose to address this problem in reflective instruments by incorporating a viewfinder pupil relay designed by considering pupil and image centering and conjugation. Diverting light from an existing pupil optical relay to the viewfinder relay allows switching field of view size. Design methods that meet all four centering and conjugation conditions using either a single concave mirror or with two concave mirrors forming an off-axis afocal telescope are presented. Two different methods for calculating the focal length and orientation of the concave mirrors in the afocal viewfinder relay are introduced. Finally, a 2.2 × viewfinder mode is demonstrated in an AO scanning light ophthalmoscope.