22 Dokumente gefunden

Three-dimensional light field fundus imaging : automatic determination of diagnostically relevant optic nerve head parameters

Purpose: Morphological changes to the optic nerve head (ONH) can be detected at the early stages of glaucoma. Three-dimensional imaging and analysis may aid in the diagnosis. Light field (LF) fundus cameras can generate three-dimensional (3D) images of optic disc topography from a single shot and are…
Rockville, Md.: Association for Research in Vision and Ophthalmology (ARVO), 2023-07-25

Modulation of human intraocular pressure using a pneumatic system

Purpose: To technically validate a novel pneumatically based system and method for modulation of intraocular pressure (IOP) and to test its application in the human eye. Special attention was paid to the applicability of the pneumatically driven balloon, which realizes the modulation of the IOP through…
Rockville, Md.: Association for Research in Vision and Ophthalmology (ARVO), 2021-12-02

Technical light-field setup for 3D imaging of the human nerve head validated with an eye model

With the new technology of 3D light field (LF) imaging, fundus photography can be expanded to provide depth information. This increases the diagnostic possibilities and additionally improves image quality by digitally refocusing. To provide depth information in the human optic nerve head such as in glaucoma…
Berlin: De Gruyter, 2021-10-09

Pulsed electrical stimulation of the human eye enhances retinal vessel reaction to flickering light

Recent studies indicate therapeutic benefits of electrical stimulation in cases of specific ophthalmic diseases that are associated with dysfunctional ocular microcirculation. This suggests effects of electrical stimulation on vascular functions. In the present study, we investigated the effects of electrical…
Lausanne: Frontiers Research Foundation, 2019-10-22

The effect of different flicker contrasts on the Dynamic Vessel Analysis

Purpose : Retinal arterioles and venules dilate when stimulated with flickering light. This phenomenon is described as functional hyperemia and closely associated with neurovascular coupling. The flicker causes a short period of heightened cellular metabolism which increases the need for blood. As a…
Rockville, Md.: ARVO, 2019-07

Amplitude changes in the electrophysiological response of retinal cells during simultaneous current stimulation

Purpose : Ocular electrical stimulation exhibit potential for the treatment of neurodegenerative ocular diseases. However, the underlying mechanism in the retinal cells remains subject of research. Studies applying transcranial electrical stimulation show that direct current stimulation (DCS) over…
Rockville, Md.: ARVO, 2019-07

Bleaching effects and fluorescence lifetime imaging ophthalmoscopy

This study investigates the influence of photopigment bleaching on autofluorescence lifetimes in the fundus in 21 young healthy volunteers. Three measurements of 30° retinal fields in two spectral channels (SSC: 498–560 nm, LSC: 560–720 nm) were obtained for each volunteer using fluorescence lifetime…
Washington, DC: Optica, 2019-03-01

The effect of different rest periods on the Dynamic Vessel Analysis

Purpose : Retinal vessels dilate when stimulated with flickering light. This phenomenon is described as functional hyperemia and closely associated with neurovascular coupling. Flicker light stimulation and investigation of the induced retinal vasodilation, known as dynamic vessel analysis (DVA), is…
Rockville, Md.: ARVO, 2018-07

Dynamic Vessel Analysis using surface-mount device LEDs as light source

Purpose : In human retinal blood flow research dynamic vessel analysis (DVA) with the Retinal Vessel Analyzer (Imedos Systems UG) is the Gold standard to measure alterations in vessel diameter. However, vessel contrast is often reduced due to stray light caused by illumination of lash, lid, or opaque…
Rockville, Md.: ARVO, 2018-07

Retinal vessel diameter variations and their correlation to arterial blood pressure

Purpose : The risk for cardiovascular diseases can be evaluated by the measuring of the retinal blood vessel diameters. Temporal variations in vessel diameter lead to uncertainties. Mayer waves are cyclic variations in cardiovascular system, which can be seen in arterial blood pressure. A link to retinal…
Rockville, Md.: ARVO, 2018-07

Dark-adapted versus bleached state in fluorescence lifetime imaging ophthalmoscopy

Purpose: The (early) detection of diseases based on metabolic changes in the retina is the goal of the novel autofluorescence lifetime ophthalmoscopy (FLIO) technique. These metabolic changes can be detected as alterations in the fundus autofluorescence (FAF) lifetimes. The influences of the photopigment…
Rockville, Md.: ARVO, 2018-07

The effect of different adaptation conditions on the dynamic vessel analysis

Purpose : Retinal arterioles and venules dilate when stimulated with flickering light. This phenomenon is described as functional hyperemia. Flicker light stimulation is an established noninvasive means of assessing the endothelial function and the retinal autoregulation by continuous measurement of…
Rockville, Md.: ARVO, 2017-06

Dynamic retinal vessel analysis using a spatial light modulator for stimulation

Purpose : Dynamic vessel analysis (DVA) with the Retinal Vessel Analyzer (Imedos Systems UG) is the Gold standard to measure alterations in retinal vessel diameter in health and disease. The DVA guidelines provide flicker stimulation of 12.5 Hz in a 30° field of view [1] (fixed full-field). However,…
Rockville, Md.: ARVO, 2017-06