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Gestational age estimation at time of birth is critical for determining the degree of prematurity of the infant and for administering appropriate postnatal treatment. We present a fully automated algorithm for estimating gestational age of premature infants through smartphone lens imaging of the anterior lens capsule vasculature (ALCV). Our algorithm uses a fully convolutional network and blind image quality analyzers to segment usable anterior capsule regions. Then, it extracts ALCV features using a residual neural network architecture and trains on these features using a support vector machine-based classifier. The classification algorithm is validated using leave-one-out cross-validation on videos captured from 124 neonates. The algorithm is expected to be an influential tool for remote and point-of-care gestational age estimation of premature neonates in low-income countries. To this end, we have made the software open source.

BACKGROUND AND OBJECTIVE: To enhance understanding of ethnically diverse normal newborn retinal morphology, the authors report spectral-domain optical coherence tomography (SD-OCT) macular findings in healthy Hispanic newborns. PATIENTS AND METHODS: In this IRB-approved prospective, observational case series, 20 full-term Hispanic newborns had dilated retinal examinations and imaging by hand-held SD-OCT without sedation at the Duke Birthing Center. RESULTS: Of 20 newborns imaged (35% male; median gestational age: 39 weeks; range: 36 to 40 weeks), two (10%) had bilateral subfoveal fluid, including one case of bilateral double subretinal fluid pockets. Three eyes of two infants (10%) had retinal macular cystoid structures (one enlarged at 1.5 months, with resolution by 3 months). These SD-OCT findings were not visible by indirect ophthalmoscopy. CONCLUSION: Some Hispanic newborns have sub-retinal fluid or macular cystoid structures on SD-OCT. This study expands our understanding of findings seen by SD-OCT in healthy full-term newborns of various races. [ Ophthalmic Surg Lasers Imaging Retina . 2013;44:448–454.]

Drusen and migrating retinal pigment epithelium have been associated with hyperreflective foci (HF) detected by spectral-domain optical coherence tomography (SD-OCT). This study sought to quantify the change in intraretinal HF distribution and its correlation with age-related macular degeneration (AMD) disease progression.Prospective observational study from the multicenter Age-Related Eye Disease Study 2 (AREDS2) Ancillary SD-OCT Study.Patients (n=299) with 1 enrolled eye with intermediate AMD and baseline SD-OCT, followed by SD-OCT imaging at 1-year and 2-year visits.The number and location of HF were scored in SD-OCT scans of all 299 eyes. The change in transverse (horizontal) and axial (vertical) distribution of HF in the macula were evaluated with pairwise signed-rank tests. Two-year inner retinal HF migration was determined by the change in HF-weighted axial distribution (AxD) score calculated for each eye. The correlation of HF with SD-OCT features of AMD progression was evaluated with logistic regression analysis.The mean change in number of HF, transverse and axial distribution of HF in the macula, and AxD per eye.In 299 study eyes, the 2-year increase in the number of HF (P0.001) and the AxD (P0.001) per eye represented longitudinal proliferation and shift to inner retinal layers, respectively. Eyes with geographic atrophy (GA) at 2 years were correlated with the presence of baseline HF (P0.001; odds ratio [OR], 4.72; 95% confidence interval [CI], 2.43-9.80), greater number of baseline HF (P0.001; OR, 1.61 per HF; 95% CI, 1.32-2.00), and greater baseline AxD (P0.001; OR, 1.58 per AxD point; 95% CI, 1.29-1.95).Proliferation and inner retinal migration of SD-OCT HF occurred during follow-up in eyes with intermediate AMD. These characteristics were associated with greater incidence of GA at year 2; therefore, SD-OCT HF proliferation and migration may serve as biomarkers for AMD progression.Proprietary or commercial disclosure may be found after the references.

We demonstrate the usefulness of utilizing a segmentation step for improving the performance of sparsity based image reconstruction algorithms. In specific, we will focus on retinal optical coherence tomography (OCT) reconstruction and propose a novel segmentation based reconstruction framework with sparse representation, termed segmentation based sparse reconstruction (SSR). The SSR method uses automatically segmented retinal layer information to construct layer-specific structural dictionaries. In addition, the SSR method efficiently exploits patch similarities within each segmented layer to enhance the reconstruction performance. Our experimental results on clinical-grade retinal OCT images demonstrate the effectiveness and efficiency of the proposed SSR method for both denoising and interpolation of OCT images.

Minimally-invasive microsurgery has resulted in improved outcomes for patients. However, operating through a microscope limits depth perception and fixes the visual perspective, which result in a steep learning curve to achieve microsurgical proficiency. We introduce a surgical imaging system employing four-dimensional (live volumetric imaging through time) microscope-integrated optical coherence tomography (4D MIOCT) capable of imaging at up to 10 volumes per second to visualize human microsurgery. A custom stereoscopic heads-up display provides real-time interactive volumetric feedback to the surgeon. We report that 4D MIOCT enhanced suturing accuracy and control of instrument positioning in mock surgical trials involving 17 ophthalmic surgeons. Additionally, 4D MIOCT imaging was performed in 48 human eye surgeries and was demonstrated to successfully visualize the pathology of interest in concordance with preoperative diagnosis in 93% of retinal surgeries and the surgical site of interest in 100% of anterior segment surgeries. In vivo 4D MIOCT imaging revealed sub-surface pathologic structures and instrument-induced lesions that were invisible through the operating microscope during standard surgical maneuvers. In select cases, 4D MIOCT guidance was necessary to resolve such lesions and prevent post-operative complications. Our novel surgical visualization platform achieves surgeon-interactive 4D visualization of live surgery which could expand the surgeon’s capabilities.

PURPOSE: To determine whether longitudinal changes in mesopic visual function on microperimetry occurred independent of its associations with microstructural parameters on spectral-domain optical coherence tomography (SD-OCT) in the early stages of AMD. METHODS: Forty-one AMD eyes underwent microperimetry testing and SD-OCT scans over a 12-month period at 6-month intervals. Microstructural parameters analyzed include the retinal pigment epithelium-drusen complex (RPEDC) layer thickness, number of hyperreflective foci (HF) and their inner retinal migration (represented by a weighted axial distribution score; AxD), and the number of atrophic areas. RESULTS: Microperimetric sensitivity was 0.29 dB (95% confidence interval [CI] = -0.38 to -0.20 dB, P < 0.001) and 0.13 dB (95% CI = -0.22 to -0.03 dB, P = 0.008) lower in each sector for every 10-μm higher RPEDC layer thickness and 1-HF present, but was not associated with the AxD score or the number of atrophic areas present (P ≤ 0.464). However, each 10-μm greater RPEDC layer thickness and 1-HF present was not independently associated with a further decline in sensitivity (-0.08 dB/year, 95% CI = -0.24 to 0.07 dB/year, P = 0.288 and 0.09 dB/year, 95% CI = -0.06 to 0.24 dB/year, P = 0.242, respectively) over time when accounting for the association between RPEDC layer thickness and number of HF with microperimetric sensitivity. CONCLUSIONS: Longitudinal changes in mesopic visual function measured on microperimetry paralleled changes in the microstructural changes over a 12-month time frame, without any changes occurring independent of the associations between structure and function alone.

Muller glia, the most abundant glia of vertebrate retina, have an elaborate morphology characterized by a vertical stalk that spans the retina and branches in each retinal layer. Muller glia play diverse, critical roles in retinal homeostasis, which are presumably enabled by their complex anatomy. However, much remains unknown, particularly in mouse, about the anatomical arrangement of Muller cells and their arbors, and how these features arise in development. Here we use membrane-targeted fluorescent proteins to reveal the fine structure of mouse Muller arbors. We find sublayer-specific arbor specializations within the inner plexiform layer (IPL) that occur consistently at defined laminar locations. We then characterize Muller glia spatial patterning, revealing how individual cells collaborate to form a pan-retinal network. Muller cells, unlike neurons, are spread across the retina with homogenous density, and their arbor sizes change little with eccentricity. Using Brainbow methods to label neighboring cells in different colors, we find that Muller glia tile retinal space with minimal overlap. The shape of their arbors is irregular but nonrandom, suggesting that local interactions between neighboring cells determine their territories. Finally, we identify a developmental window at postnatal Days 6 to 9 when Muller arbors first colonize the synaptic layers beginning in stereotyped inner plexiform layer sublaminae. Together, our study defines the anatomical arrangement of mouse Muller glia and their network in the radial and tangential planes of the retina, in development and adulthood. The local precision of Muller glia organization suggests that their morphology is sculpted by specific cell to cell interactions with neurons and each other.

Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disorder that may have anterior visual pathway involvement. In this study, we compare the macular structure of patients with ALS to healthy controls and examine correlations between macular sub-layer thickness measurements and pulmonary function tests and disease duration. ALS patients underwent optical coherence tomography (OCT) imaging to obtain macular cube scans of the right eye. Macular cube OCT data from age-matched healthy subjects were provided by the OCT reading center. Semi-automated retinal segmentation software was used to quantify macular sub-layers. Pulmonary function tests and time since symptom onset were collected retrospectively from the electronic medical records of ALS patients. Macular retinal nerve fiber layer was significantly thinner in ALS patients compared to healthy controls (P P

PURPOSE To develop image analysis software usable by nonexpert graders to segment geographic atrophy (GA) from dry AMD and to quantify rim area focal hyperautofluorescence (RAFH) surrounding GA on fundus autofluorescence (FAF) images. To compare the GA progression predictions based on RAFH with those of a validated qualitative classification system. METHODS Retrospective analysis of serial FAF images from 49 eyes of 30 subjects with GA was performed using MATLAB-based software (MathWorks, Natick, MA, USA). Correlation between RAFH and progression of GA was analyzed using Spearman correlation. Comparisons of lesion growth rate between RAFH tertiles used generalized estimating equations and Kruskal-Wallis testing. Interobserver variability in lesion size, growth rate and RAFH were compared between two expert and one nonexpert grader using Bland-Altman statistics. RESULTS Rim area focal hyperautofluorescence was positively correlated with GA progression rate (ρ = 0.49, P < 0.001). Subjects in the middle or highest RAFH tertile were at greater risk of progression (P = 0.005 and P = 0.001, respectively). Mean difference in RAFH was 0.012 between expert and -0.005 to 0.017 between expert and nonexperts. Mean difference in lesion size (mm2) was 0.11 between expert and -0.29 to 0.41 between expert and nonexperts. Mean difference in lesion growth rate (mm2/mo) was 0.0098 between expert and -0.027 to 0.037 between expert and nonexperts. Risk stratification based on RAFH tertile was 96% identical across all graders. CONCLUSIONS Our semiautomated image analysis software facilitates stratification of progression risk based on RAFH and enabled a nonexpert grader with minimal training to obtain results comparable to expert graders. Predictions based on RAFH were similar to those of a validated qualitative classification system.

In vivo photoreceptor imaging has enhanced the way vision scientists and ophthalmologists understand the retinal structure, function, and etiology of numerous retinal pathologies. However, the complexity and large footprint of current systems capable of resolving photoreceptors has limited imaging to patients who are able to sit in an upright position and fixate for several minutes. Unfortunately, this excludes an important fraction of patients including bedridden patients, small children, and infants. Here, we show that our dual-modality, high-resolution handheld probe with a weight of only 94 g is capable of visualizing photoreceptors in supine children. Our device utilizes a microelectromechanical systems (MEMS) scanner and a novel telescope design to achieve over an order of magnitude reduction in size compared to similar systems. The probe has a 7° field of view and a lateral resolution of 8 µm. The optical coherence tomography (OCT) system has an axial resolution of 7 µm and a sensitivity of 101 dB. High definition scanning laser ophthalmoscopy (SLO) and OCT images were acquired from children ranging from 14 months to 12 years of age with and without pathology during examination under anesthesia in the operating room. Parafoveal cone imaging was shown using the SLO arm of this device without adaptive optics using a 3° FOV for the first time in children under 4 years old. This work lays the foundation for pediatric research, which will improve understanding of retinal development, maldevelopment and early onset of diseases at the cellular level during the beginning stages of human growth.

The human retina is composed of several layers, visible by in vivo optical coherence tomography (OCT) imaging. To enhance diagnostics of retinal diseases, several algorithms have been developed to automatically segment one or more of the boundaries of these layers. OCT images are corrupted by noise, which is frequently the result of the detector noise and speckle, a type of coherent noise resulting from the presence of several scatterers in each voxel. However, it is unknown what the empirical distribution of noise in each layer of the retina is, and how the magnitude and distribution of the noise affects the lower bounds of segmentation accuracy. Five healthy volunteers were imaged using a spectral domain OCT probe from Bioptigen, Inc, centered at 850nm with 4.6µm full width at half maximum axial resolution. Each volume was segmented by expert manual graders into nine layers. The histograms of intensities in each layer were then fit to seven possible noise distributions from the literature on speckle and image processing. Using these empirical noise distributions and empirical estimates of the intensity of each layer, the Cramer-Rao lower bound (CRLB), a measure of the variance of an estimator, was calculated for each boundary layer. Additionally, the optimum bias of a segmentation algorithm was calculated, and a corresponding biased CRLB was calculated, which represents the improved performance an algorithm can achieve by using prior knowledge, such as the smoothness and continuity of layer boundaries. Our general mathematical model can be easily adapted for virtually any OCT modality.

Inducing angiogenesis is one hallmark of cancer. Tumor induced neovasculature is often characterized as leaky, tortuous and chaotic, unlike a highly organized normal vasculature. Additionally, in the course of carcinogenesis, angiogenesis precedes a visible lesion. Tumor cannot grow beyond 1-2 mm in diameter without inducing angiogenesis. Therefore, capturing the event of angiogenesis may aid early detection of pre-cancer –important for better treatment prognoses in regions that lack the resources to manage invasive cancer. In this study, we imaged the neovascularization in vivo in a spontaneous hamster cheek pouch carcinogen model using a, non-invasive, label-free, high resolution, reflected-light spectral darkfield microscope. Hamsters’ cheek pouches were painted with 7,12-Dimethylbenz[a]anthracene (DMBA) to induce pre-cancerous to cancerous changes, or mineral oil as control. High resolution spectral darkfield images were obtained over the course of pre-cancer development and in control cheek pouches. The vasculature was segmented with a multi-scale Gabor filter with an 85% accuracy compared with manually traced masks. Highly tortuous vasculature was observed only in the DMBA treated cheek pouches as early as 6 weeks of treatment. In addition, the highly tortuous vessels could be identified before a visible lesion occurred later during the treatment. The vessel patterns as determined by the tortuosity index were significantly different from that of the control cheek pouch. This preliminary study suggests that high-resolution darkfield microscopy is promising tool for pre-cancer and early cancer detection in low resource settings.

Patient motion artifacts are an important source of data irregularities in OCT imaging. With longer duration OCT scans – as is needed for large wide field of view scans or increased scan density – motion artifacts become increasingly problematic. Strategies to mitigate these motion artifacts are then necessary to ensure OCT data integrity. A popular strategy for reducing motion artifacts in OCT images is to capture two orthogonally oriented volumetric scans containing uncorrelated motion and subsequently reconstructing a motion-free volume by combining information from both datasets. While many different variations of this registration approach have been proposed, even the most recent methods might not be suitable for wide FOV OCT scans which can be lacking in features away from the optic nerve head or arcades. To address this problem, we propose a two-stage motion correction algorithm for wide FOV OCT volumes. In the first step, X and Y axes motion is corrected by registering OCT summed voxel projections (SVPs). To achieve this, we introduce a method based on a custom variation of the dense optical flow technique which is aware of the motion free orientation of the scan. Secondly, a depth (Z axis) correction approach based on the segmentation of the retinal layer boundaries in each B-scan using graph-theory and dynamic programming is applied. This motion correction method was applied to wide field retinal OCT volumes (approximately 80° FOV) of 3 subjects with substantial reduction in motion artifacts.

Optical coherence tomography (OCT) allows for micron scale imaging of the human retina and cornea. Current generation research and commercial intrasurgical OCT prototypes are limited to live B-scan imaging. Our group has developed an intraoperative microscope integrated OCT system capable of live 4D imaging. With a heads up display (HUD) 4D imaging allows for dynamic intrasurgical visualization of tool tissue interaction and surgical maneuvers. Currently our system relies on operator based manual tracking to correct for patient motion and motion caused by the surgeon, to track the surgical tool, and to display the correct B-scan to display on the HUD. Even when tracking only bulk motion, the operator sometimes lags behind and the surgical region of interest can drift out of the OCT field of view. To facilitate imaging we report on the development of a fast volume based tool segmentation algorithm. The algorithm is based on a previously reported volume rendering algorithm and can identify both the tool and retinal surface. The algorithm requires 45 ms per volume for segmentation and can be used to actively place the B-scan across the tool tissue interface. Alternatively, real-time tool segmentation can be used to allow the surgeon to use the surgical tool as an interactive B-scan pointer.

PurposeTo assess the reliability of manual choroidal thickness measurements by comparing different posterior boundary definitions of the choroidal-scleral junction on enhanced depth imaging optical coherence tomography (EDI-OCT).DesignReliability analysis.MethodsTwo graders marked the choroidal-scleral junction with segmentation software using different posterior boundaries: (1) the outer border of the choroidal vessel lumen, (2) the outer border of the choroid stroma, and (3) the inner border of the sclera, to measure the vascular choroidal thickness (VCT), stromal choroidal thickness (SCT), and total choroidal thickness (TCT), respectively. Measurements were taken at 0.5-mm intervals from 1.5mm nasal to 1.5mm temporal to the fovea, and averaged continuously across the central 3mm of the macula. Intraclass correlation coefficient (ICC) and coefficient of reliability (CR) were compared to assess intergrader and intragrader reliability.ResultsChoroidal thickness measurements varied significantly with different posterior boundaries (P < .001 for all). Intergrader ICCs were greater for SCT (0.959-0.980) than for TCT (0.928-0.963) and VCT (0.750-0.869), even in eyes where choroidal-scleral junction visibility was

Visual impairment due to glaucoma currently impacts 70 million people worldwide. While disease progression can be slowed or stopped with effective lowering of intraocular pressure, current medical treatments are often inadequate. Fortunately, three new classes of therapeutics that target the diseased conventional outflow tissue responsible for ocular hypertension are in the final stages of human testing. The rho kinase inhibitors have proven particularly efficacious and additive to current therapies. Unfortunately, non-contact technology that monitors the health of outflow tissue and its response to conventional outflow therapy is not available clinically. Using optical coherence tomographic (OCT) imaging and novel segmentation software, we present the first demonstration of drug effects on conventional outflow tissues in living eyes. Topical netarsudil (formerly AR-13324), a rho kinase/ norepinephrine transporter inhibitor, affected both proximal (trabecular meshwork and Schlemm’s Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract. Hence, increased perfusion of outflow tissues was reliably resolved by OCT as widening of the trabecular meshwork and significant increases in cross-sectional area of Schlemm’s canal following netarsudil treatment. These changes occurred in conjunction with increased outflow facility, increased speckle variance intensity of outflow vessels, increased tracer deposition in conventional outflow tissues and decreased intraocular pressure. This is the first report using live imaging to show real-time drug effects on conventional outflow tissues and specifically the mechanism of action of netarsudil in mouse eyes. Advancements here pave the way for development of a clinic-friendly OCT platform for monitoring glaucoma therapy.

Purpose Structural and compositional heterogeneity within drusen comprising lipids, carbohydrates, and proteins have been previously described. We sought to detect and define phenotypic patterns of drusen heterogeneity in the form of optical coherence tomography–reflective drusen substructures (ODS) and examine their associations with age-related macular degeneration (AMD)–related features and AMD progression. Design Retrospective analysis in a prospective study. Participants Patients with intermediate AMD (n = 349) enrolled in the multicenter Age-Related Eye Disease Study 2 (AREDS2) ancillary spectral-domain optical coherence tomography (SD OCT) study. Methods Baseline SD OCT scans of 1 eye per patient were analyzed for the presence of ODS. Cross-sectional and longitudinal associations of ODS presence with AMD-related features visible on SD OCT and color photographs, including drusen volume, geographic atrophy (GA), and preatrophic features, were evaluated for the entire macular region. Similar associations were also made locally within a 0.5-mm-diameter region around individual ODS and corresponding control region without ODS in the same eye. Main Outcome Measures Preatrophy SD OCT changes and GA, central GA, and choroidal neovascularization (CNV) from color photographs. Results Four phenotypic subtypes of ODS were defined: low reflective cores, high reflective cores, conical debris, and split drusen. Among the 349 participants, there were 307 eligible eyes and 74 (24%) had at least 1 ODS. The ODS at baseline were associated with (1) greater macular drusen volume at baseline ( P P = 0.001–0.01), and (3) development of macular GA ( P = 0.005) and preatrophic changes at year 3 ( P = 0.002–0.008), but not development of CNV. The ODS at baseline in a local region were associated with (1) presence of preatrophy changes at baseline ( P = 0.02–0.03) and (2) development of preatrophy changes at years 2 and 3 within the region ( P = 0.008–0.05). Conclusions Optical coherence tomography–reflective drusen substructures are optical coherence tomography–based biomarkers of progression to GA, but not to CNV, in eyes with intermediate AMD. Optical coherence tomography–reflective drusen substructures may be a clinical entity helpful in monitoring AMD progression and informing mechanisms in GA pathogenesis.

We introduce a metric in graph search and demonstrate its application for segmenting retinal optical coherence tomography (OCT) images of macular pathology. Our proposed “adjusted mean arc length” (AMAL) metric is an adaptation of the lowest mean arc length search technique for automated OCT segmentation. We compare this method to Dijkstra’s shortest path algorithm, which we utilized previously in our popular graph theory and dynamic programming segmentation technique. As an illustrative example, we show that AMAL-based length-adaptive segmentation outperforms the shortest path in delineating the retina/vitreous boundary of patients with full-thickness macular holes when compared with expert manual grading.

A handheld probe enables retinal imaging in children. Enabled by adaptive optics, retinal photoreceptor cell imaging is changing our understanding of retinal structure1,2 and function3,4, as well as the pathogenesis of numerous ocular diseases5. To date, use of this technology has been limited to cooperative adult subjects due to the size, weight and inconvenience of the equipment, thus excluding study of retinal maturation during human development. Here, we report the design and operation of a handheld probe that can perform both scanning laser ophthalmoscopy and optical coherence tomography of the parafoveal photoreceptor structure in infants and children without the need for adaptive optics. The probe, featuring a compact optical design weighing only 94 g, was able to quantify packing densities of parafoveal cone photoreceptors and visualize cross-sectional photoreceptor substructure in children with ages ranging from 14 months to 12 years. The probe will benefit paediatric research by improving the understanding of retinal development, maldevelopment and early onset of disease during human growth.

Vascularisation of the macula takes place between 24 and 27 weeks post-conception. Preterm birth may affect the formation of the foveal avascular zone (FAZ) and foveal depression, and displacement of inner retinal layers away from the incipient fovea.To examine whether vascular abnormalities accompany an inner retinal abnormality, and whether they are coincident.High-density spectral domain optical coherence tomography volume scans were obtained from 24 preterm children and 34 full-term controls (5-16 years). Matlab programs were used to quantify total retinal thickness, thickness of individual retinal layers and metrics of foveal morphology. Summed voxel projections for the ganglion cell layer-inner nuclear layer were used to identify the FAZ.Preterm children had significantly smaller FAZ diameters than controls (p0.0001). The foveal pits of preterm children were significantly shallower and less steep (p0.0001) and total retinal thickness at the fovea was significantly increased (p0.0001) compared to controls. The ganglion cell layer-inner plexiform layer and outer nuclear layer were significantly (p≤0.0001) thicker in preterm children than in controls.Preterm birth results in abnormal foveal vascularisation, a failure of the inner retinal neurons to migrate away from the fovea, and an elevated outer nuclear layer ratio. The spatial coincidence of inner retinal and vascular abnormalities in preterm children supports the hypothesis that aspects of foveal development are interdependent.

This paper presents a generalized framework for segmenting closed-contour anatomical and pathological features using graph theory and dynamic programming (GTDP). More specifically, the GTDP method previously developed for quantifying retinal and corneal layer thicknesses is extended to segment objects such as cells and cysts. The presented technique relies on a transform that maps closed-contour features in the Cartesian domain into lines in the quasi-polar domain. The features of interest are then segmented as layers via GTDP. Application of this method to segment closed-contour features in several ophthalmic image types is shown. Quantitative validation experiments for retinal pigmented epithelium cell segmentation in confocal fluorescence microscopy images attests to the accuracy of the presented technique.

In this paper, we make contact with the field of compressive sensing and present a development and generalization of tools and results for reconstructing irregularly sampled tomographic data. In particular, we focus on denoising Spectral-Domain Optical Coherence Tomography (SDOCT) volumetric data. We take advantage of customized scanning patterns, in which, a selected number of B-scans are imaged at higher signal-to-noise ratio (SNR). We learn a sparse representation dictionary for each of these high-SNR images, and utilize such dictionaries to denoise the low-SNR B-scans. We name this method multiscale sparsity based tomographic denoising (MSBTD). We show the qualitative and quantitative superiority of the MSBTD algorithm compared to popular denoising algorithms on images from normal and age-related macular degeneration eyes of a multi-center clinical trial. We have made the corresponding data set and software freely available online.

Mice are a common animal model for studies of aqueous humor dynamics and outflow physiology. The anatomy of the conventional outflow pathway in mice is similar to that of humans with a continuous Schlemm's canal and lamellated trabecular meshwork.1 Like primates, mice possess a ciliary muscle that forms tendinous connections to the elastic fiber net of the trabecular meshwork and the inner wall endothelium of Schlemm's canal.2 Compounds that affect outflow facility in humans, including pilocarpine,2,3 TGF-β2,4,5 latanoprost6–8 prostaglandin EP4 receptor agonist,9–11 and sphingosine 1-phosphate,11,12 similarly affect outflow facility in mice. Recently, mice have been used to validate novel compounds that increase outflow facility based on hits from screening assays of cellular contractility.13 Numerous investigators have measured outflow facility in mice.2,5,6,8,11,14–26 However, on account of the small dimensions of the mouse eye and the low flow rates involved, there is greater potential for physical factors to influence ocular perfusion measurements in mice compared with larger species. For example, evaporation from the surface of the eye, which is more pronounced in smaller eyes that have a larger surface to volume ratio, may lead to dehydration of the corneoscleral shell and artifactually increase the apparent outflow rate. Importantly, this effect would manifest as a pressure-independent outflow during perfusion. Posterior bowing of the iris, known as anterior chamber (AC) deepening, artificially increases outflow facility by applying traction to the trabecular meshwork.27,28 Anterior chamber deepening typically occurs during ocular perfusion via the AC, when the pressure in the AC exceeds that in the posterior chamber (PC). The pressure difference causes the iris–lens channel to collapse like a 1-way valve, preventing pressure equilibration across the iris. Anterior chamber deepening can be prevented by perfusion via the PC, by creating a fluidic shunt across the iris,29 or by iridectomy.30 Note that AC deepening is not synonymous with ‘AC depth,' which represents the distance between the posterior cornea and anterior lens. Because mice have a relatively large crystalline lens, it has been proposed that AC deepening may be negligible in mice,18 but this has not been specifically examined. To address these gaps in knowledge, this study examined the influence of hydration and AC deepening on pressure-dependent and pressure-independent outflow in enucleated mouse eyes. We also examined the effect of temperature that could account for up to 40% variation in apparent outflow facility due to changes in water viscosity between room and physiological temperature.

Super-resolution (SR) is the process of combining multiple aliased low-quality images to produce a high-resolution high-quality image. Aside from registration and fusion of low-resolution images, a key process in SR is the restoration and denoising of the fused images. We present a novel extension of the combined Fourier-wavelet deconvolution and denoising algorithm ForWarD to the multiframe SR application. Our method first uses a fast Fourier-base multiframe image restoration to produce a sharp, yet noisy estimate of the high-resolution image. Our method then applies a space-variant nonlinear wavelet thresholding that addresses the nonstationarity inherent in resolution-enhanced fused images. We describe a computationally efficient method for implementing this space-variant processing that leverages the efficiency of the fast Fourier transform (FFT) to minimize complexity. Finally, we demonstrate the effectiveness of this algorithm for regular imagery as well as in digital mammography.

Scanning laser ophthalmoscopy (SLO) and spectral domain optical coherence tomography (SDOCT) have become essential clinical diagnostic tools in ophthalmology by allowing for video-rate noninvasive en face and depth-resolved visualization of retinal structure. Current generation multimodal imaging systems that combine both SLO and OCT as a means of image tracking remain complex in their hardware implementations. Here, we combine a spectrally encoded confocal scanning laser ophthalmoscope (SECSLO) with an ophthalmic SDOCT system. This novel implementation of an interlaced SECSLO-SDOCT system allows for video-rate SLO fundus images to be acquired alternately with high-resolution SDOCT B-scans as a means of image aiming, guidance, and registration as well as motion tracking. The system shares the illumination source, detection system, and scanning optics between both SLO and OCT as a method of providing a simple multimodal ophthalmic imaging system that can readily be implemented as a table-top or hand-held device.

Inner retina in Alzheimer's Disease (AD) may experience neuroinflammation resulting in atrophy. The objective of our study was to determine whether retinal GCIPL (ganglion cell-inner plexiform layer) or nerve fiber layer (NFL) thickness may serve as noninvasive biomarkers to diagnose AD. This cross-sectional case-control study enrolled 15 mild cognitive impairment (MCI) patients, 15 mild-moderate AD patients, and 18 cognitively normal adults. NFL and GCIPL thicknesses on optical coherence tomography (OCT) were measured using Duke Optical Coherence Tomography Retinal Analysis Program (DOCTRAP) and Spectralis software. We demonstrated that regional thicknesses of NFL or GCIPL on macular or nerve OCTs did not differ between groups. However, a multi-variate regression analysis identified macular areas with a significant thickening or thinning in NFL and GCIPL in MCI and AD patients. Our primary findings controvert previous reports of thinner NFL in moderate-to-severe AD. The areas of thickening of GCIPL and NFL in the macula adjacent to areas of thinning, as revealed by a more complex statistical model, suggest that NFL and GCIPL may undergo dynamic changes during AD progression.

In this paper, we present a new technique to calculate the power dissipation profile from the IC temperature map using a process analogous to image processing and restoration. In this technique, finite-element analysis (FEA) is used to find the heat-point spread function (heat PSF) of the IC chip. Then, the temperature map is used as input for an efficient image restoration algorithm which locates the sources of strong power dissipation non-uniformities. Therefore, it optimally solves the inverse heat transfer problem, and estimates the IC power map without extensive lab experiments. Our computationally efficient and robust method, unlike some previous techniques, applies to many experimental scenarios. Simulation results on a typical commercial integrated circuit chip confirm the effectiveness of our proposed method.

Kernel regression is an effective tool for a variety of image processing tasks such as denoising and interpolation [1]. In this paper, we extend the use of kernel regression for deblurring applications. In some earlier examples in the literature, such nonparametric deblurring was suboptimally performed in two sequential steps, namely denoising followed by deblurring. In contrast, our optimal solution jointly denoises and deblurs images. The proposed algorithm takes advantage of an effective and novel image prior that generalizes some of the most popular regularization techniques in the literature. Experimental results demonstrate the effectiveness of our method.

Accurate registration of images is the most important and challenging aspect of multiframe image restoration problems such as super-resolution. The accuracy of super-resolution algorithms is quite often limited by the ability to register a set of low-resolution images. The main challenge in registering such images is the presence of aliasing. In this paper, we analyse the problem of jointly registering a set of aliased images and its relationship to super-resolution. We describe a statistically optimal approach to multiframe registration which exploits the concept of variable projections to achieve very efficient algorithms. Finally, we demonstrate how the proposed algorithm offers accurate estimation under various conditions when standard approaches fail to provide sufficient accuracy for super-resolution.

Tree-like structures are fundamental in nature, and it is often useful to reconstruct the topology of a tree - what connects to what - from a two-dimensional image of it. However, the projected branches often cross in the image: the tree projects to a planar graph, and the inverse problem of reconstructing the topology of the tree from that of the graph is ill-posed. We regularize this problem with a generative, parametric tree-growth model. Under this model, reconstruction is possible in linear time if one knows the direction of each edge in the graph - which edge endpoint is closer to the root of the tree - but becomes NP-hard if the directions are not known. For the latter case, we present a heuristic search algorithm to estimate the most likely topology of a rooted, three-dimensional tree from a single two-dimensional image. Experimental results on retinal vessel, plant root, and synthetic tree data sets show that our methodology is both accurate and efficient.

We propose a novel, graph-theoretic framework for distinguishing arteries from veins in a fundus image. We make use of the underlying vessel topology to better classify small and midsized vessels. We extend our previously proposed tree topology estimation framework by incorporating expert, domain-specific features to construct a simple, yet powerful global likelihood model. We efficiently maximize this model by iteratively exploring the space of possible solutions consistent with the projected vessels. We tested our method on four retinal datasets and achieved classification accuracies of 91.0%, 93.5%, 91.7%, and 90.9%, outperforming existing methods. Our results show the effectiveness of our approach, which is capable of analyzing the entire vasculature, including peripheral vessels, in wide field-of-view fundus photographs. This topology-based method is a potentially important tool for diagnosing diseases with retinal vascular manifestation.

We assessed the reproducibility of lateral and axial measurements performed with spectral-domain optical coherence tomography (SDOCT) instruments from a single manufacturer and across several manufacturers. One human retina phantom was imaged on two instruments each from four SDOCT platforms: Zeiss Cirrus, Heidelberg Spectralis, Bioptigen SDOIS, and hand-held Bioptigen Envisu. Built-in software calipers were used to perform manual measurements of a fixed lateral width (LW), central foveal thickness (CFT), and parafoveal thickness (PFT) 1 mm from foveal center. Inter- and intraplatform reproducibilities were assessed with analysis of variance and Tukey-Kramer tests. The range of measurements between platforms was 5171 to 5290 μm for mean LW (p

BACKGROUND To apply automated spectral domain optical coherence tomography (SD-OCT) segmentation to eyes with resolving papilledema. METHODS Ninety-four patients with idiopathic intracranial hypertension seen at the Duke Eye Center neuro-ophthalmology clinic between November 2010 and October 2011 were reviewed. Excluded were eyes with papilledema with Frisen grade >2, other optic neuropathies or retinopathies, and those that did not have SD-OCT imaging. The remaining 43 patients were split into 2 groups: non-atrophic papilledema and atrophic papilledema. Automated SD-OCT segmentation was performed on patients with non-atrophic papilledema and age-matched controls for each of the 9 regions of the Early Treatment Diabetic Retinopathy Study map. Bonferroni correction was used for multiple comparisons. All SD-OCT scans were reviewed for retinal structural abnormalities. RESULTS Total macular thickness was significantly thinner within the fovea and inner macular ring in non-atrophic papilledema vs control eyes (266 vs 276 μm, P = 0.04; 333 vs 344 μm P < 0.01, n = 26 non-atrophic papilledema, 30 controls). SD-OCT demonstrated thinning within the fovea, inner macular ring, and outer macular ring of the outer plexiform layer plus nuclear layer in non-atrophic papilledema vs control (124 vs 131 μm, P < 0.01; 112 vs 118 μm, P = 0.03; 95 vs 100 μm, P = 0.03). Retinal structural changes were seen in 21/33 eyes with atrophic papilledema vs none of the eyes with non-atrophic papilledema or controls. CONCLUSIONS SD-OCT shows qualitative and quantitative changes in the macula of eyes with resolved papilledema.

Handheld scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) systems facilitate imaging of young children and subjects that have difficulty fixating. More compact and lightweight probes allow for better portability and increased comfort for the operator of the handheld probe. We describe a very compact, novel SLO and OCT handheld probe design. A single 2D microelectromechanical systems (MEMS) scanner and a custom optical design using a converging beam prior to the scanner permitted significant reduction in the system size. Our design utilized a combination of commercial and custom optics that were optimized in Zemax to achieve near diffraction-limited resolution of 8 μm over a 7° field of view. The handheld probe has a form factor of 7 x 6 x 2.5 cm and a weight of only 94 g, which is over an order of magnitude lighter than prior SLO-OCT handheld probes. Images were acquired from a normal subject with an incident power on the eye under the ANSI limit. With this device, which is the world’s lightest and smallest SLO-OCT system, we were able to visualize parafoveal cone photoreceptors and nerve fiber bundles without the use of adaptive optics.

To create and validate software to automatically segment leakage area in real-world clinical fluorescein angiography (FA) images of subjects with diabetic macular edema (DME).Fluorescein angiography images obtained from 24 eyes of 24 subjects with DME were retrospectively analyzed. Both video and still-frame images were obtained using a Heidelberg Spectralis 6-mode HRA/OCT unit. We aligned early and late FA frames in the video by a two-step nonrigid registration method. To remove background artifacts, we subtracted early and late FA frames. Finally, after postprocessing steps, including detection and inpainting of the vessels, a robust active contour method was utilized to obtain leakage area in a 1500-μm-radius circular region centered at the fovea. Images were captured at different fields of view (FOVs) and were often contaminated with outliers, as is the case in real-world clinical imaging. Our algorithm was applied to these images with no manual input. Separately, all images were manually segmented by two retina specialists. The sensitivity, specificity, and accuracy of manual interobserver, manual intraobserver, and automatic methods were calculated.The mean accuracy was 0.86 ± 0.08 for automatic versus manual, 0.83 ± 0.16 for manual interobserver, and 0.90 ± 0.08 for manual intraobserver segmentation methods.Our fully automated algorithm can reproducibly and accurately quantify the area of leakage of clinical-grade FA video and is congruent with expert manual segmentation. The performance was reliable for different DME subtypes. This approach has the potential to reduce time and labor costs and may yield objective and reproducible quantitative measurements of DME imaging biomarkers.

We present a novel general-purpose compression method for tomographic images, termed 3D adaptive sparse representation based compression (3D-ASRC). In this paper, we focus on applications of 3D-ASRC for the compression of ophthalmic 3D optical coherence tomography (OCT) images. The 3D-ASRC algorithm exploits correlations among adjacent OCT images to improve compression performance, yet is sensitive to preserving their differences. Due to the inherent denoising mechanism of the sparsity based 3D-ASRC, the quality of the compressed images are often better than the raw images they are based on. Experiments on clinical-grade retinal OCT images demonstrate the superiority of the proposed 3D-ASRC over other well-known compression methods.

We present a fully automatic algorithm to identify fluid-filled regions and seven retinal layers on spectral domain optical coherence tomography images of eyes with diabetic macular edema (DME). To achieve this, we developed a kernel regression (KR)-based classification method to estimate fluid and retinal layer positions. We then used these classification estimates as a guide to more accurately segment the retinal layer boundaries using our previously described graph theory and dynamic programming (GTDP) framework. We validated our algorithm on 110 B-scans from ten patients with severe DME pathology, showing an overall mean Dice coefficient of 0.78 when comparing our KR + GTDP algorithm to an expert grader. This is comparable to the inter-observer Dice coefficient of 0.79. The entire data set is available online, including our automatic and manual segmentation results. To the best of our knowledge, this is the first validated, fully-automated, seven-layer and fluid segmentation method which has been applied to real-world images containing severe DME.

Purpose To measure average retinal nerve fiber layer (RNFL) thicknesses in healthy, full-term neonates. Design Descriptive research to develop normative data. Methods Healthy infants born between 37 and 42 weeks postmenstrual age were imaged with hand-held spectral-domain optical coherence tomography. A custom script segmented the RNFL; the fovea and optic nerve center were manually selected. A second script measured the average RNFL thickness along the papillomacular bundle, defined as the arc from −15 degrees to +15 degrees on the axis from the optic nerve to fovea, with radii of 1.1, 1.3, 1.5, and 1.7 mm from the center of the optic disc. Shapiro-Wilk W tests assessed these measurements for normality to determine the age-appropriate radial distance for subsequent analyses. Average RNFL thicknesses for four temporal 45-degree sectors (superior temporal, temporal superior, temporal inferior, and inferior temporal) and the temporal quadrant were calculated and compared to demographic parameters for all infants. Results Fifty full-term infants were adequately imaged for RNFL analysis. RNFL thicknesses at 1.5 mm radial distance from the optic nerve were the most normally distributed. While there was a trend toward greater mean superior temporal RNFL thickness for both black and Hispanic vs white infants (128 ± 27 μm, 124 ± 30 μm, and 100 ± 19 μm, respectively, P = .04 for both comparisons), there were no other significant differences noted in RNFL thicknesses by race, sex, gestational age, or birth weight. Conclusions We present RNFL thickness measurements for healthy, full-term infants that may serve as normative data for future analyses.

PurposeTo determine the effect of anti-vascular endothelial growth factor (VEGF) therapy on choroidal thickness in eyes with diabetic macular edema (DME).DesignA retrospective, cohort analysis of 59 eyes from 59 patients with DME without prior anti-VEGF therapy.MethodsChoroidal thickness was measured using semiautomated segmentation of enhanced depth imaging optical coherence tomography images at 0.5-mm intervals from 2.5 mm nasal to 2.5 mm temporal to the fovea. Changes in choroidal thickness with and without anti-VEGF treatment over 6 months were compared. Best-corrected visual acuity and central foveal thickness were analyzed to evaluate the association of choroidal thickness with functional and anatomic outcomes.ResultsOf the 59 eyes with DME, 26 eyes were observed without treatment, whereas 33 underwent intravitreal anti-VEGF therapy (mean number of injections, 2.73) over 6 months. In untreated eyes, there was no significant change in best-corrected visual acuity (P = .098), central foveal thickness (P = .472), or choroidal thickness at all measurements along the macula (P = .057 at the fovea). In eyes treated with anti-VEGF injections, choroidal thickness decreased significantly at the fovea (246.6 to 224.8 μm; P < .001) and at 0.5 mm nasal (240.9 to 221.9 μm; P = .002) and 0.5 mm temporal (249.3 to 224.8 μm; P = .011) to the fovea. The decrease in subfoveal choroidal thickness after anti-VEGF treatment was not associated with the cumulative number of anti-VEGF injections (R(2) = 0.031; P = .327) or to changes in best-corrected visual acuity (R(2) = 0.017; P = .470) or central foveal thickness (R(2) = 0.040; P = .263).ConclusionsCentral choroidal thickness decreases after anti-VEGF therapy for DME after 6 months, but may not be associated with functional or anatomic outcomes in eyes with DME.

Arti” cial neural networks are intelligent systems that have been successfully used for prediction in different medical ” elds. In this study, ef” ciency of neural networks for prediction of lupus nephritis in patients with systemic lupus erythematosus (SLE) was compared with a logistic regression model and clinicians’diagnosis. Overall accuracy, sensitivity and speci” city of the optimal neural network were 68.69, 73.77 and 62.96%, respectively. Overall accuracy of neural network was greater than the other two methods (P-value< 0.05). The neural network was more speci” c in predicting lupus nephritis (P-value < 0.01), but there was no signi” cant difference between sensitivities of the three methods. Sensitivities of all three methods were greater than their speci” cities. We concluded that neural networks are ef” cient in predicting lupus nephritis in SLE patients.

Age-related macular degeneration (AMD) is a major cause of vision loss in the elderly. To better study the pathobiology of AMD, postmortem eyes offer an excellent opportunity to correlate optical coherence tomography (OCT) imaging characteristics with histopathology. However, postmortem eyes from autopsy present challenges to standard OCT imaging including opaque anterior segment structures and standard of care autopsy processing resulting in oblique views to the macula. To overcome these challenges, we report a custom periscope attached by a standard mount to an OCT sample arm and demonstrate high quality macular OCT acquisitions in autopsy-processed eyes.

We present a novel framework combining convolutional neural networks (CNN) and graph search methods (termed as CNN-GS) for the automatic segmentation of nine layer boundaries on retinal optical coherence tomography (OCT) images. CNN-GS first utilizes a CNN to extract features of specific retinal layer boundaries and train a corresponding classifier to delineate a pilot estimate of the eight layers. Next, a graph search method uses the probability maps created from the CNN to find the final boundaries. We validated our proposed method on 60 volumes (2915 B-scans) from 20 human eyes with non-exudative age-related macular degeneration (AMD), which attested to effectiveness of our proposed technique.

Purpose We determine whether the automated segmentation software, Duke Optical Coherence Tomography Retinal Analysis Program (DOCTRAP), can measure, in a platform-independent manner, retinal thickness on Cirrus and Spectralis spectral domain optical coherence tomography (SD-OCT) images in eyes with diabetic macular edema (DME) under treatment in a clinical trial. Methods Automatic segmentation software was used to segment the internal limiting membrane (ILM), inner retinal pigment epithelium (RPE), and Bruch's membrane (BM) in SD-OCT images acquired by Cirrus and Spectralis commercial systems, from the same eye, on the same day during a clinical interventional DME trial. Mean retinal thickness differences were compared across commercial and DOCTRAP platforms using intraclass correlation (ICC) and Bland-Altman plots. Results The mean 1 mm central subfield thickness difference (standard error [SE]) comparing segmentation of Spectralis images with DOCTRAP versus HEYEX was 0.7 (0.3) μm (0.2 pixels). The corresponding values comparing segmentation of Cirrus images with DOCTRAP versus Cirrus software was 2.2 (0.7) μm. The mean 1 mm central subfield thickness difference (SE) comparing segmentation of Cirrus and Spectralis scan pairs with DOCTRAP using BM as the outer retinal boundary was -2.3 (0.9) μm compared to 2.8 (0.9) μm with inner RPE as the outer boundary. Conclusions DOCTRAP segmentation of Cirrus and Spectralis images produces validated thickness measurements that are very similar to each other, and very similar to the values generated by the corresponding commercial software in eyes with treated DME. Translational relevance This software enables automatic total retinal thickness measurements across two OCT platforms, a process that is impractical to perform manually.

The effective speed of a swept source optical coherence tomography (SSOCT) imaging system was quadrupled using efficient sweep buffering along with coherence revival and spatial multiplexing. A polarizing beam splitter and fold mirror assembly were used to create a dual spot sample arm with a common objective designed for near-diffraction-limited retinal imaging. Using coherence revival, a variable optical delay line allowed for separate locations within a sample to be simultaneously imaged and frequency encoded by carefully controlling the optical path length of each sample path. This method can be used to efficiently quadruple the imaging speed of any SSOCT system employing a low duty-cycle laser that exhibits coherence revival. The system was used to image the retina of healthy human volunteers.

To identify changes in retinal function and structure in persons with proliferative diabetic retinopathy (PDR), including the effects of panretinal photocoagulation (PRP).Cross-sectional study.Thirty adults who underwent PRP for PDR, 15 adults with untreated PDR, and 15 age-matched controls.Contrast sensitivity, frequency doubling perimetry (FDP), Humphrey visual fields, photostress recovery, and dark adaptation were assessed. Fundus photography and macular spectral-domain optical coherence tomography (SD OCT) were performed. To quantify retinal layer thicknesses, SD OCT scans were segmented semiautomatically.Visual function measures were compared among patients with PDR and PRP, untreated patients with PDR, and controls. Mean retinal layer thicknesses were compared between groups. Correlation analyses were performed to evaluate associations between visual function measures and retinal layer thicknesses.A significant reduction of FDP mean deviation (MD) was exhibited in PRP-treated patients with PDR (MD ± standard deviation, -8.20±5.76 dB; P0.0001) and untreated patients (-5.48±4.48 dB; P0.0001) relative to controls (1.07±2.50 dB). Reduced log contrast sensitivity compared with controls (1.80±0.14) also was observed in both PRP-treated patients (1.42±0.17; P0.0001) and untreated patients (1.56±0.20; P = 0.001) with PDR. Compared with controls, patients treated with PRP demonstrated increased photostress recovery time (151.02±104.43 vs. 70.64±47.14 seconds; P = 0.001) and dark adaptation speed (12.80±5.15 vs. 9.74±2.56 minutes; P = 0.022). Patients who underwent PRP had diffusely thickened nerve fiber layers (P = 0.024) and diffusely thinned retinal pigment epithelium (RPE) layers (P = 0.009) versus controls. Untreated patients with PDR also had diffusely thinned RPE layers (P = 0.031) compared with controls.Patients with untreated PDR exhibited inner retinal dysfunction, as evidenced by reduced contrast sensitivity and FDP performance, accompanied by alterations in inner and outer retinal structure. Patients who underwent PRP had more profound changes in outer retinal structure and function. Distinguishing the effects of PDR and PRP may guide the development of restorative vision therapies for patients with advanced diabetic retinopathy.

Purpose The goal was to assess effects of IOP and pilocarpine-induced ciliary muscle contraction on conventional outflow pathway tissues in living anesthetized mice. Methods Intraocular pressure was controlled by intracameral cannulation of mouse eyes while imaging using spectral-domain optical coherence tomography (SD-OCT). Time-lapse sagittal SD-OCT sections through Schlemm's canal (SC) were acquired while changing IOP stepwise between 10 and 45 mm Hg. After topical application of 1% pilocarpine, the series of IOP steps and imaging were repeated. Effects of pilocarpine on IOP and outflow facility in living mice were verified by rebound tonometry and flow measurements at three different IOPs, respectively. In vivo OCT images were compared with eyes analyzed by standard histology. Results In living mice imaged by SD-OCT, the lumen of SC progressively collapsed with increasing IOP, reaching near complete closure at 20 mm Hg. Schlemm's canal collapse was reversible, with the lumen opening within minutes after returning IOP from 45 to 10 mm Hg. Pilocarpine-induced ciliary muscle contraction changed SC lumen area by 131.6% ± 21.0% compared with untreated controls at 10 mm Hg, opened the trabecular meshwork, and prevented complete collapse of the SC lumen at higher pressures. Similar results were observed by standard histology. Pilocarpine increased outflow facility 4-fold (P = 0.02) and lowered IOP (16.46 ± 2.23 vs. 11.08 ± 2.28 mm Hg, P = 0.03). Conclusions Spectral-domain OCT was effective at visualizing changes in SC lumen in living mice. Results with pilocarpine are consistent with the concept that a primary role for the ciliary muscle is to prevent collapse of SC.

We assessed the reproducibility of lateral and axial measurements performed with spectral-domain optical coherence tomography (SDOCT) instruments from a single manufacturer and across several manufacturers. One human retina phantom was imaged on two instruments each from four SDOCT platforms: Zeiss Cirrus, Heidelberg Spectralis, Bioptigen SDOIS, and hand-held Bioptigen Envisu. Built-in software calipers were used to perform manual measurements of a fixed lateral width (LW), central foveal thickness (CFT), and parafoveal thickness (PFT) 1 mm from foveal center. Inter- and intraplatform reproducibilities were assessed with analysis of variance and Tukey-Kramer tests. The range of measurements between platforms was 5171 to 5290 μm for mean LW (p

Optical coherence tomography angiography (OCTA) is a promising technique for non-invasive visualization of vessel networks in the human eye. We debut a system capable of acquiring wide field-of-view (>70°) OCT angiograms without mosaicking. Additionally, we report on enhancing the visualization of peripheral microvasculature using wavefront sensorless adaptive optics (WSAO). We employed a fast WSAO algorithm that enabled wavefront correction in