Response of capillaries and small arterioles to full-field flicker is not dependent on local ganglion cell thickness.

To measure the influence of ganglion cell layer (GCL) thickness on the changes in size and red blood cell (RBC) flow in small retinal vessels evoked by full-field flicker. We used a dual-beam adaptive optics scanning laser ophthalmoscope to image 11 healthy young controls in two retinal areas with significantly different GCL thicknesses. All capillaries and arterioles of the superficial vascular plexus were responsive to the flicker stimulation.

Photoreceptor layer elevation due to subretinal fluid: Impact on visual acuity measurements and simulation from biometrics.

Purpose: Visual acuity (VA) is a primary outcome measure that defines the success of clinical interventions for retinal diseases such as age-related macular degeneration (AMD) or diabetic macular oedema (DME). These conditions can lead to the presence of subretinal fluid, causing substantial photoreceptor layer elevation. Hyperopic defocus then occurs, affecting the VA measurements.

Advancements in high-resolution imaging of the iridocorneal angle.

High-resolution imaging methods of the iridocorneal angle (ICA) will lead to enhanced understanding of aqueous humor outflow mechanisms and a characterization of the trabecular meshwork (TM) morphology at the cellular level will help to better understand glaucoma mechanics (e.g., cellular level biomechanics of the particulate glaucomas).

Potential vision tester using adaptive optics, Maxwellian view, and small pupil.

We demonstrate a free-space, trolley-mounted potential vision tester (PVT), designed to study and improve the accuracy of visual acuity (VA) measurements in the aging eye. Key features include a high-resolution visual display presented in Maxwellian view, a 3 mm pupil to limit wavefront (WF) aberrations, and a moderate cost deformable mirror to induce or correct higher order optical aberrations. The visual display supported accurate measurement of visual acuities down to 20/5.

Clinically significant macular edema in an underserved population: Association with demographic factors and hemoglobin A1c.

Significance: Suspected clinically significant macular edema (SCSME) from exudates differed among ethnic groups in our underserved population. African American and Asian subjects had higher prevalence than Hispanics and non-Hispanic Caucasians, from the same clinics. Men had higher prevalence than women.

Retinal Arteriolar Wall Remodeling in Diabetes Captured With AOSLO.

Purpose: Adaptive optics scanning laser ophthalmoscopy (AOSLO) enables the visualization and measurement of the retinal microvasculature structure in humans. We investigated the hypothesis that diabetes mellitus (DM) induces remodeling to the wall structure in small retinal arterioles. These alterations may allow better understanding of vascular remodeling in DM.

Imaging fine structures of the human trabecular meshwork using a custom design goniolens and OCT gonioscopy.

The trabecular meshwork (TM), located within the iridocorneal angle, is a target for many glaucoma treatments aimed at controlling intraocular pressure. However, structural variations between individuals are poorly understood. We propose a newly designed gonioscopic lens optimized for high-resolution imaging to image fine structures of the human TM .

Characterization of the human iridocorneal angle using a custom design goniolens with OCT gonioscopy.

Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma progression, and many treatments target the trabecular meshwork (TM). Imaging this region is challenging due to optical limitations of imaging through the cornea at high angles. We propose a gonioscopic OCT approach using a custom goniolens and a commercially available OCT device to improve imaging of the TM, Schlemm's canal (SC) and adjacent structures within the iridocorneal angle (ICA).

Cone Photoreceptors in Diabetic Patients.

Purpose: Cones in diabetic patients are at risk due to metabolic and vascular changes. By imaging retinal vessel modeling at high magnification, we reduced its impact on cone distribution measurements. The retinal vessel images and retinal thickness measurements provided information about cone microenvironment.

Measuring Temporal and Spatial Variability of Red Blood Cell Velocity in Human Retinal Vessels.

Purpose: The retinal circulation regulates blood flow through various internal and external factors; however, it is unclear how locally these factors act within the retinal microcirculation. We measured the temporal and spatial variability of blood velocity in small retinal vessels using a dual-beam adaptive optics scanning laser ophthalmoscope.

Methods: In young healthy subjects (n = 3), temporal blood velocity variability was measured in a local vascular region consisting of an arteriole, capillary, and venule repeatedly over 2 days.

Imaging the Retinal Vasculature.

Advances in retinal imaging are enabling researchers and clinicians to make precise noninvasive measurements of the retinal vasculature in vivo. This includes measurements of capillary blood flow, the regulation of blood flow, and the delivery of oxygen, as well as mapping of perfused blood vessels. These advances promise to revolutionize our understanding of vascular regulation, as well as the management of retinal vascular diseases.

Identifying predictors and evaluating the role of steroids in the prevention of post-embolization syndrome after transarterial chemoembolization and bland embolization.

Background: Transarterial chemoembolization (TACE) and bland embolization (TAE), performed for hepatocellular carcinoma (HCC), are often complicated by post-embolization syndrome (PES). There are limited data regarding the incidence of PES after TAE and the role of steroids in PES. We report the incidence of PES post TACE and TAE, identify predictors, and evaluate the role of steroids in PES.

Presumed activated retinal astrocytes and Müller cells in healthy and glaucomatous eyes detected by spectral domain optical coherence tomography.

Purpose: To investigate presumed activated retinal astrocytes and Müller cells (ARAM) detected by scanning laser ophthalmoscopy (SLO) and spectral domain optical coherence tomography, and to investigate its presence in healthy controls as well as its relationship to posterior vitreal detachment (PVD) and glaucoma.

Methods: This retrospective study involved 1337 eyes of 805 controls between ages 8 and 90, and 250 eyes of 146 patients with glaucoma between the ages of 28 and 95. Subjects were counted as possessing ARAM only if they met the following criteria: (1) a patchy, discrete, glittering appearance on SLO, (2) a distinct, flat, hyper-reflective layer at the internal limiting membrane on at least one B-scan crossing the glittering area and (3) absence of any surface wrinkling retinopathy.

Cones in ageing and harsh environments: the neural economy hypothesis.

Purpose: Cones are at great risk in a wide variety of retinal diseases, especially when there is a harsh microenvironment and retinal pigment epithelium is damaged. We provide established and new methods for assessing cones and retinal pigment epithelium, together with new results. We investigated conditions under which cones can be imaged and could guide light, despite the proximity of less than ideal retinal pigment epithelium.

High-Resolution, Adaptive Optics Imaging of the Human Trabecular Meshwork In Vivo.

Purpose: To image the human trabecular meshwork (TM) in vivo using adaptive optics gonioscopy (AOG) with approximately 2-μm lateral resolution.

Methods: An existing Indiana University adaptive optics scanning laser ophthalmoscope was altered by adding a 12-mm button lens to a clinical gonioscopic lens allowing high-resolution imaging of the human iridocorneal angle. First an anatomic model eye was used to refine the imaging technique and then nine participants (7 controls and 2 participants with pigment dispersion syndrome) were imaged.

Central Macular Thickness in Diabetic Patients: A Sex-based Analysis.

Significance: The pathological changes in clinically significant diabetic macular edema lead to greater retinal thickening in men than in women. Therefore, male sex should be considered a potential risk factor for identifying individuals with the most severe pathological changes. Understanding this excessive retinal thickening in men may help preserve vision.

Adaptive optics imaging of the human retina.

Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time.

Alterations to the Foveal Cone Mosaic of Diabetic Patients.

Purpose: We measured localized changes occurring in the foveal cone photoreceptors and related defects in the cone mosaic to alterations in the nearby retinal vasculature.

Methods: The central 4° of the retina of 54 diabetic (53.7 ± 12.

Retinal Vascular Branching in Healthy and Diabetic Subjects.

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).

SD-OCT and Adaptive Optics Imaging of Outer Retinal Tubulation.

Purpose: To investigate outer retinal tubulation (ORT) using spectral domain optical coherence tomography (SD-OCT) and an adaptive optics scanning laser ophthalmoscope (AOSLO). To document the frequency of ORT in atrophic retinal conditions and quantify ORT dimensions versus adjacent retinal layers.

Methods: SD-OCT images were reviewed for the presence of retinal atrophy, scarring, and/or exudation.

A Computational Model of Peripheral Photocoagulation for the Prevention of Progressive Diabetic Capillary Occlusion.

We developed a computational model of the propagation of retinal ischemia in diabetic retinopathy and analyzed the consequences of various patterns and sizes of burns in peripheral retinal photocoagulation. The model addresses retinal ischemia as a phenomenon of adverse local feedback in which once a capillary is occluded there is an elevated probability of occlusion of adjacent capillaries resulting in enlarging areas of retinal ischemia as is commonly seen clinically. Retinal burns of different sizes and patterns, treated as local oxygen sources, are predicted to have different effects on the propagation of retinal ischemia.

Comparison of Cysts in Red and Green Images for Diabetic Macular Edema.

Purpose: To investigate whether cysts in diabetic macular edema are better visualized in the red channel of color fundus camera images, as compared with the green channel, because color fundus camera screening methods that emphasize short-wavelength light may miss cysts in patients with dark fundi or changes to outer blood retinal barrier.

Methods: Fundus images for diabetic retinopathy photoscreening were acquired for a study with Aeon Imaging, EyePACS, University of California Berkeley, and Indiana University. There were 2047 underserved, adult diabetic patients, of whom over 90% self-identified as a racial/ethnic identify other than non-Hispanic white.

Retinal Arterioles in Hypo-, Normo-, and Hypertensive Subjects Measured Using Adaptive Optics.

Purpose: Small artery and arteriolar walls thicken due to elevated blood pressure. Vascular wall thickness show a correlation with hypertensive subject history and risk for stroke and cardiovascular events.

Methods: The inner and outer diameter of retinal arterioles from less than 10 to over 150 μm were measured using a multiply scattered light adaptive optics scanning laser ophthalmoscope (AOSLO).

Progression of Diabetic Capillary Occlusion: A Model.

An explanatory computational model is developed of the contiguous areas of retinal capillary loss which play a large role in diabetic maculapathy and diabetic retinal neovascularization. Strictly random leukocyte mediated capillary occlusion cannot explain the occurrence of large contiguous areas of retinal ischemia. Therefore occlusion of an individual capillary must increase the probability of occlusion of surrounding capillaries.

Non-mydriatic confocal retinal imaging using a digital light projector.

A digital light projector is implemented as an integrated illumination source and scanning element in a confocal non-mydriatic retinal camera, the Digital Light Ophthalmoscope (DLO). To simulate scanning, a series of illumination lines are rapidly projected on the retina. The backscattered light is imaged onto a 2-dimensional rolling shutter CMOS sensor.