Exploring single-mode VCSEL wavelength tuning for low-cost 3D optical coherence tomography and OCT angiography.

Low-cost optical coherence tomography has recently emerged as a growing field due to the increased need for general availability of OCT devices outside of the clinics. One of the main obstacles in creating low-cost SS-OCT systems is the price of the laser. In this work, we study the influence of different tuning parameters (e.

Introduction and Validation of Low-Cost Ocular Biometry in Healthy and Cataractous Eyes Using a Thermally Tunable Swept-Source Laser.

Purpose: To introduce and validate a novel substantially lower-priced and rapid swept-source investigational optical biometer in healthy and cataractous eyes, using a thermally tuned laser diode used extensively in cell phones and data communication as an alternative swept source.

Design: Prospective accuracy, validity, and reliability analysis.

Methods: A total of 60 eyes of 59 subjects (29 eyes of 29 healthy subjects and 31 eyes of 30 cataract patients) were enrolled in a prospective comparative study at the Vienna General Hospital between August 2021 and April 2023.

PRESERFLO™ Microshunt: 1-Year Results of a 25-Gauge vs. 27-Gauge Needle Tract.

The purpose of this study was to evaluate the effectiveness and safety of the PreserFlo™ microshunt (PMS) using a 25-Gauge vs. 27-Gauge needle tract. : This is a prospective postoperative examination of 60 glaucoma eyes that received a PMS.

Thermally tuned VCSEL at 850 nm as a low-cost alternative source for full-eye SS-OCT.

Swept-source optical coherence tomography (SS-OCT) demonstrates superior performance in comparison to spectral domain OCT with regard to depth ranging. The main driver of cost for SS-OCT systems is, however, the price of the source. Here we show a low-cost alternative swept source that uses a thermally tuned vertical-cavity surface-emitting laser (VCSEL) at 850 nm.

Birefringent Properties of the Peripapillary Retinal Nerve Fiber Layer in Healthy and Glaucoma Subjects Analyzed by Polarization-Sensitive OCT.

Purpose: To study the circumpapillary retinal nerve fiber layer (RNFL) birefringence (BIR) of early glaucoma and age-matched healthy eyes using polarization-sensitive optical coherence tomography (PS-OCT).

Methods: In this prospective cross-sectional study, we compared virtual circular PS-OCT B-scans with a diameter of 3.5 mm centered on the optic disc (OD) acquired with a PS-OCT prototype (860 nm center wavelength).

Retinal Oxygen Extraction in Patients with Primary Open-Angle Glaucoma.

Objective: To compare total retinal oxygen extraction between patients with primary open-angle glaucoma (POAG) and healthy control subjects. Design: A prospective, single-center, cross-sectional, case−control study performed at the Medical University of Vienna. Subjects: Forty patients with POAG and 40 age- and sex-matched control subjects.

Automatic retinal nerve fiber bundle tracing based on large field of view polarization sensitive OCT data.

A technique to accurately estimate trajectories of retinal nerve fiber bundles (RNFB) in a large field of view (FOV) image covering 45° is described. The method utilizes stitched projections of polarization-sensitive optical coherence tomography (PS-OCT) data, as well as a mathematical model of average RNFB trajectories as prior. The fully automatic process was applied to data recorded in healthy subjects and glaucoma patients and automatically detected individual RNFB trajectories are compared to manual traces.

Optical coherence tomography-measured retinal nerve fiber layer thickness values compensated with a multivariate model and discrimination between stable and progressing glaucoma suspects.

Purpose: Our previously introduced multivariate model, compensating for intersubject variability, was applied to circumpapillary retinal nerve fiber layer (RNFL) values measured with optical coherence tomography in glaucoma suspects with or without prior progressive optic disc (OD) change in a series of confocal scanning laser tomography (CSLT, HRT III) measurements.

Methods: In this prospective study, OD change during CSLT follow-up was determined with strict, moderate, and liberal criteria of the topographic change analysis (TCA). Model compensation (MC) as well as age compensation (AC) was applied to RNFL sectors (RNFLMC vs.

Needling and open filtering bleb revision after XEN-45 implantation-a retrospective outcome comparison.

Purpose: To compare efficacy and safety of needling and open bleb revision after XEN-45 surgery.

Methods: This retrospective study represents real-life data of patients who underwent XEN-45 surgery between November 2014 and June 2018 in the Vienna General Hospital. The following groups were formed for data evaluation: (PSEA) primary surgery secondary intervention allowed (n = 268); (PS) primary surgery until secondary intervention (n = 268); (N) first needling until additional secondary intervention (n = 55); (BR) first bleb revision until additional secondary intervention (n = 105).

Generating large field of view en-face projection images from intra-acquisition motion compensated volumetric optical coherence tomography data.

A technique to generate large field of view projection maps of arbitrary optical coherence tomography (OCT) data is described. The technique is divided into two stages - an image acquisition stage that features a simple to use fast and robust retinal tracker to get motion free retinal OCT volume scans - and a stitching stage where OCT data from different retinal locations is first registered against a reference image using a custom pyramid-based approach and finally stitched together into one seamless large field of view (FOV) image. The method is applied to data recorded with a polarization sensitive OCT instrument in healthy subjects and glaucoma patients.

Comparison of Spectralis and Cirrus spectral domain optical coherence tomography for the objective morphometric assessment of the neuroretinal rim width.

Purpose: The assessment of cup-disc ratio as a surrogate parameter for the neuroretinal rim width (NRW) of the optic nerve is well established, but prone to human error and imprecision. Objective assessment of the NRW is provided by spectral domain optical coherence tomography (SD-OCT). This study is the first to systematically compare NRW measurements acquired with the Carl Zeiss Meditech Cirrus HD-OCT 5000 and the Heidelberg Engineering Spectralis SD-OCT.

Optic nerve head morphology in primary open-angle glaucoma and nonarteritic anterior ischaemic optic neuropathy measured with spectral domain optical coherence tomography.

Purpose: Optic nerve head (ONH) parameters as well as circumpapillary retinal nerve fibre layer (RNFL) thickness values measured with two different spectral domain optical coherence tomography (SD-OCT) machines (Spectralis and Cirrus OCT) have been compared between two patient groups, primary open-angle glaucoma (POAG), nonarteritic anterior ischaemic optic neuropathy (NAION) and healthy controls. A comparison of the performance of the two OCT machines was made.

Methods: Twenty healthy controls, 20 POAG and 20 NAION patients with comparable visual field defects were included.

Optic nerve head blood flow regulation during changes in arterial blood pressure in patients with primary open-angle glaucoma.

Purpose: Abnormal autoregulation of optic nerve head blood flow (ONHBF) has been postulated to play an important role in primary open-angle glaucoma (POAG). We used laser Doppler flowmetry (LDF) to estimate quantitatively the ONHBF and compared ONHBF autoregulation between glaucoma patients and healthy controls during isometric exercise.

Methods: Forty patients with POAG and 40 healthy age- and sex-matched subjects underwent three periods of isometric exercise, each consisting of 2 min of handgripping.

A Functional Regression Model of the Retinal Nerve Fiber Layer Thickness in Healthy Subjects.

Purpose: A new functional regression model is presented to explain the intersubject variability of the circumpapillary retinal nerve fiber layer (RNFL) thickness in healthy subjects.

Methods: To evaluate the functional regression approach we used data from 202 healthy volunteers, divided equally into training samples (TS) and validation samples (VS). Covariates included RNFL, fovea distance, fovea angle, optic disk ratio, orientation and area provided by Fourier-domain-optical coherence tomography, age, and refractive error.

Influence of disc-fovea angle and retinal blood vessels on interindividual variability of circumpapillary retinal nerve fibre layer.

Background: To assess whether intersubject variability of circumpapillary retinal nerve fibre layer (RNFL) thickness in healthy subjects acquired with spectral domain optical coherence tomography (SD-OCT) can be reduced by considering the disc-fovea angle (DFA), either alone or together with a compensation based on retinal blood vessel distribution (RVD).

Methods: 106 healthy volunteers underwent SD-OCT examination centred on the optic disc (OD) and on the macula. OD contours and foveal positions were automatically calculated.

Multivariate Model of the Intersubject Variability of the Retinal Nerve Fiber Layer Thickness in Healthy Subjects.

Purpose: We present and validate a multivariate model that partially compensates for retinal nerve fiber layer (RNFL) intersubject variability.

Methods: A total of 202 healthy volunteers randomly attributed to a training (TS) and a validation (VS) sample underwent complete ophthalmic examination, including Fourier-domain optical coherence tomography (FD-OCT). We acquired FD-OCT data centered at the optic disc (OD) and the macula.

Compensation for retinal vessel density reduces the variation of circumpapillary RNFL in healthy subjects.

This work intends to assess circumpapillary retinal vessel density (RVD) at a 3.46 mm diameter circle and correlate it with circumpapillary retinal nerve fiber layer (RNFL) thickness measured with Fourier-Domain Optical Coherence Tomography. Furthermore, it aims to evaluate the reduction of intersubject variability of RNFL when considering RVD as a source of information for RNFL distribution.

Retinal Blood Vessel Distribution Correlates With the Peripapillary Retinal Nerve Fiber Layer Thickness Profile as Measured With GDx VCC and ECC.

Purpose: Aim of the present study was to evaluate whether there is a correlation between retinal blood vessel density (RVD) and the peripapillary retinal nerve fiber layer (RNFL) thickness profile.

Methods: RNFL thickness of 106 healthy subjects was measured using scanning laser polarimetry, GDx variable corneal compensation (VCC), and GDx enhanced corneal compensation (ECC). A proprietary software was developed in MATLAB to measure the peripapillary retinal vessels using scanning laser ophthalmoscopy fundus images, centered on the optic disc measured by Cirrus spectral domain optical coherence tomography.

Correlation between retinal vessel density profile and circumpapillary RNFL thickness measured with Fourier-domain optical coherence tomography.

Aim: To assess circumpapillary retinal vessel density (RVD) profiles and correlate them with retinal nerve fibre layer (RNFL) thickness measured by Fourier domain optical coherence tomography (FD-OCT).

Methods: RNFL thickness of 106 healthy volunteers was measured using Cirrus FD-OCT. A proprietary software was developed in MATLAB to assess the thickness and position of circumpapillary retinal vessels using the scanning laser ophthalmoscopy fundus image, centred on the optic disc.

A double-masked randomized crossover study comparing the effect of latanoprost/timolol and brimonidine/timolol fixed combination on intraocular pressure and ocular blood flow in patients with primary open-angle glaucoma or ocular hypertension.

Purpose: Ocular blood flow dysregulation has been implicated in the pathogenesis of glaucoma. Whereas the effect of single antiglaucoma substances on ocular blood flow has been addressed in various experiments, evidence for fixed combinations is sparse. In the present study, we set out to compare the effects of latanoprost 0.

Comparison of optic disc parameters using spectral domain cirrus high-definition optical coherence tomography and confocal scanning laser ophthalmoscopy in normal eyes.

Purpose: To compare Cirrus HD - optical coherence tomography (HD-OCT) with confocal scanning laser ophthalmoscopy (HRT 3) for analysis of optic disc parameters in healthy eyes.

Methods: In 126 subjects, cup volume (CV), vertical cup/disc ratio (CDR), neuroretinal rim area (NRA), cup area (CA) and optic disc area (ODA) were measured with the Cirrus HD-OCT and HRT 3. These optic disc parameters were chosen for statistical analysis because they can be analysed in both OCT and HRT 3 and they are widely used parameters for glaucoma assessment.

Effect of regular smoking on flicker induced retinal vasodilatation in healthy subjects.

Background: Habitual smoking is a risk factor for a variety of vascular diseases, including ocular pathologies. In the current study, we set out to investigate whether the regulation of retinal vascular tone is impaired in habitual smokers. For this purpose, vascular reactivity was tested during flicker light induced vasodilatation in smokers and in a non-smoking control group.

Role of adenosine in the control of choroidal blood flow during changes in ocular perfusion pressure.

Purpose: The purpose of the present study was to investigate whether the nucleoside adenosine is involved in the regulatory processes of choroidal blood flow (ChBF) during an experimental decrease in ocular perfusion pressure (OPP).

Methods: In this randomized, double-masked, placebo-controlled, two-way crossover study, 14 subjects received either intravenous adenosine or placebo on two different study days. The suction cup method was used for a stepwise increase in intraocular pressure (IOP).

Correlation of optic disc morphology and ocular perfusion parameters in patients with primary open angle glaucoma.

Purpose: Little information is available about the relationship between glaucomatous visual field defects, morphological changes of the optic disc and ocular blood flow. In this study, ocular blood flow parameters were correlated with parameters of optic nerve head (ONH) morphology and visual field performance in a cross-sectional study.

Methods: A total of 103 patients with primary open angle glaucoma were included.

Effect of latanoprost on choroidal blood flow regulation in healthy subjects.

Purpose: The present study tested the hypothesis that human choroidal blood flow (ChBF) regulation in the face of changes in ocular perfusion pressure (OPP) may be modified by a drug-induced decrease in intraocular pressure (IOP).

Methods: This hypothesis was tested in a double-masked, randomized, placebo-controlled, parallel-group trial in 24 healthy volunteers. OPP was manipulated by 6 minutes of squatting and a subsequent period of artificial increase in IOP induced with a suction cup.