Publications by authors named "Torsten Strasser"

Introduction: Light is a key factor in moderating human alertness, both subjective and objective. However, the methodology applies in research on the effects of exposure to light of different wavelengths and intensities on objective and subjective alertness varies greatly and evidence on objective alertness in particular is still inconclusive. Thus, the present, highly standardized within-subject laboratory study on N = 44 healthy males explored how LED light of different intensities (dim vs.

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Purpose: Investigating influencing factors on the pupillary light response (PLR) as a biomarker for local retinal function by providing epidemiological data of a large normative collective and to establish a normative database for the evaluation of chromatic pupil campimetry (CPC).

Methods: Demographic and ophthalmologic characteristics were captured and PLR parameters of 150 healthy participants (94 women) aged 18 to 79 years (median = 46 years) were measured with L-cone- and rod-favoring CPC protocols. Linear-mixed effects models were performed to determine factors influencing the PLR and optical coherence tomography (OCT) data were correlated with the pupillary function volume.

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Article Synopsis
  • The Preserflo MicroShunt is a new treatment for primary open-angle glaucoma, focusing on forming a bleb to lower intraocular pressure, with long-term effects still under study.
  • A study involving 62 eyes showed significant reductions in intraocular pressure after 24 months, with no notable decline in corneal endothelial cell density.
  • Success rates were relatively high, with over half of the patients achieving target pressures without medication, and overall best corrected visual acuity remained stable throughout the study period.
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Presbyopia is an age-related ocular condition, typically affecting individuals aged over 40 years, characterized by a gradual and irreversible decline in the eye's ability to focus on nearby objects. Correction methods for presbyopia encompass the use of corrective lenses, surgical interventions (corneal or lens based), and, more recently, the FDA-approved topical administration of 1.25% pilocarpine.

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Purpose: Verifying whether specific genotypes causing retinitis pigmentosa (RP) show differences in the preservation of rod and cone function measured by chromatic pupil campimetry (CPC).

Methods: Sixty-three RP eyes (37 male, 14-58 years) were measured using CPC with specific photopic and scotopic protocols, and the relative maximal constriction amplitudes and latencies to constriction onset were analyzed per genotype (RP due to variants in EYS, n = 14; PDE6A, n = 10; RPE65, n = 15; USH2A, n = 10; and RPGR, n = 14). Correlation analyses between the pupillary responses were performed with age, full-field stimulus threshold (FST), and optical coherence tomography (OCT) for cones and rods, respectively, to the genotype.

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Environmental factors favoring myopia development are still being studied and there is accumulating evidence for a significant role of nearwork. Recently, reading standard black-on-white text was found to activate the retinal OFF pathway and induce choroidal thinning, which is associated with myopia onset. Contrarily, reading white-on-black text led to thicker choroids, being protective against myopia.

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Purpose: To quantify visual performance of patients with achromatopsia at various contrast and luminance combinations typical for daily living conditions, in comparison to controls, and to measure beneficial effects of short-wavelength cutoff filter glasses used by patients with achromatopsia to reduce glare sensation.

Methods: Best-corrected visual acuity (BCVA) was tested with Landolt rings using an automated device (VA-CAL test). The visual acuity space was assessed for each participant with and without filter glasses (transmission >550 nm) at 46 contrast-luminance combinations (18%-95%; 0-10,000 cd/m2).

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Transcorneal electrical stimulation (TES) is used as therapy for retinal diseases such as retinitis pigmentosa (RP) and was suggested for assessing retinal sensitivity by determining phosphene thresholds, subjective luminance impressions caused by retinal stimulation. Further applications concerned the accommodation process, revealing an improved accommodative amplitude in presbyopic eyes after TES treatment. The respective changes of the ciliary muscle (CM), the structure most important for near vision, during TES are yet unknown.

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Adeno-associated viral (AAV) vector suspensions produced in either human derived HEK cells or in Spodoptera frugiperda (Sf9) insect cells differ in terms of residual host cell components as well as species-specific post-translational modifications displayed on the AAV capsid proteins. Here we analysed the impact of these differences on the immunogenic properties of the vector. We stimulated human plasmacytoid dendritic cells with various lots of HEK cell-produced and Sf9 cell-produced AAV-CMV-eGFP vectors derived from different manufacturers.

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Purpose: To explore the pupil redilation during persistent light exposure (pupillary escape phenomenon) at the macula and periphery with monochromatic light stimuli.

Methods: Forty healthy subjects aged 18-64 years (24 females) were examined by chromatic pupil campimetry (CPC) using red and blue 4-s stimuli of 10° radius at the center and 20°-peripheral locations one per quadrant. One glaucoma patient and one achromatopsia patient served as disease models.

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Anterior segment optical coherence tomography (AS-OCT), being non-invasive and well-tolerated, is the method of choice for an in vivo investigation of ciliary muscle morphology and function. The analysis requires the segmentation of the ciliary muscle, which is, when performed manually, both time-consuming and prone to examiner bias. Here, we present a convolutional neural network trained for the automatic segmentation of the ciliary muscle in AS-OCT images.

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Studies on the electrical excitability of retinal neurons show that photoreceptors and other cell types can be selectively activated by distinct stimulation frequencies in vitro. Yet, this principle still needs to be validated in humans in vivo. As a first step, this study explored the frequency preferences of human rods by means of transcorneal electrostimulation (TES), using the electrically-elicited pupillary responses (EEPRs) as an objective readout.

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Article Synopsis
  • The study aimed to compare liquid crystal displays (LCD) and cathode ray tube monitors (CRT) for their effectiveness in measuring visual acuity using sweep visual evoked potentials (VEP).
  • Two experiments were conducted: the first tested 13 volunteers using both monitor types, while the second tested six volunteers with varying contrast levels, including a modern LCD gaming monitor.
  • Results indicated that LCDs had a significantly delayed response time compared to CRTs and smaller amplitude for VEPs, but these differences did not lead to a significant effect on estimated visual acuity across the methods used.
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Presbyopia describes the eye's physiological loss of the ability to see close objects clearly. The adaptation to different viewing distances, termed accommodation, is achieved by a change in the curvature of the eye lens induced by the ciliary muscle. A possible approach to correct presbyopia could be to detect the ciliary muscle's neuromuscular signals during accommodation and transfer these signals electronically to a biomimetic, micro-optical system to provide the necessary refractive power.

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Purpose: Autosomal recessive retinitis pigmentosa (arRP) can be caused by mutations in the phosphodiesterase 6A (PDE6A) gene. Here, we describe the natural course of disease progression with respect to central retinal function (i.e.

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Purpose: Best-corrected visual acuity (BCVA) is assessed at a single standardized luminance with maximum optotype contrast, not reflecting the constantly changing daily-life viewing conditions. For a more realistic estimation of visual performance at varying object contrasts (Cs) and ambient luminances (ALs), we developed a new VA test, VA-CAL.

Methods: Landolt-C-rings between 18% and 95% Weber contrast, were presented at 1 m distance (8 Alternative Forced Choice) on a 5.

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Calpains are a family of calcium-activated proteases involved in numerous disorders. Notably, previous studies have shown that calpain activity was substantially increased in various models for inherited retinal degeneration (RD). In the present study, we tested the capacity of the calpain-specific substrate -BOC-Leu-Met-CMAC to detect calpain activity in living retina, in organotypic retinal explant cultures derived from wild-type mice, as well as from and RD-mutant mice.

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Hereditary degeneration of photoreceptors has been linked to over-activation of Ca-permeable channels, excessive Ca-influx, and downstream activation of Ca-dependent calpain-type proteases. Unfortunately, after more than 20 years of pertinent research, unequivocal evidence proving significant and reproducible photoreceptor protection with Ca-channel blockers is still lacking. Here, we show that both D- and L-cis enantiomers of the anti-hypertensive drug diltiazem were very effective at blocking photoreceptor Ca-influx, most probably by blocking the pore of Ca-permeable channels.

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Purpose: To examine systematically how prechiasmal, chiasmal, and postchiasmal lesions along the visual pathway affect the respective pupillary responses to specific local monochromatic stimuli.

Methods: Chromatic pupil campimetry (CPC) was performed in three patient groups (10 subjects with status after anterior ischemic optic neuropathy, 6 with chiasmal lesions, and 12 with optic tract or occipital lobe lesions (tumor, ischemia)) using red, low-intensity red, and blue local stimuli within the central 30° visual field. Affected areas - as determined by visual field defects revealed using conventional static perimetry - were compared with non-affected areas.

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Purpose: To assess the effect of central and peripheral stimulation on the pupillary light reflex. The aim was to detect possible differences between cone- and rod-driven reactions.

Methods: Relative maximal pupil constriction amplitude (relMCA) and latency to constriction onset (latency) to cone- and rod-specific stimuli of 30 healthy participants (24 ± 5 years (standard deviation)) were measured using chromatic pupil campimetry.

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Background/aims: To evaluate the PandAcuity test for visual function testing in a paediatric cohort and to examine its agreement with conventional visual acuity (VA) testing.

Methods: PandAcuity scores were determined in 152 children (77 males) aged between 3 and 15 years after VA testing (LEA-test, E-chart, Landolt-C-rings or numbers). The PandAcuity test consisted of illusions made up from silhouettes of animals 'hidden' within zig-zag-patterns of decreasing spatial frequencies.

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Purpose To evaluate clinical outcome after surgery of idiopathic epiretinal membranes (ERM) with internal limiting membrane (ILM) peeling using a commercial combination of Brilliant blue G (BBG, 0.25 mg/ml) with 4% polyethylene glycol (PEG). Methods It was a prospective, single-center study.

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This work presents a quick clinical protocol for dark-adapted chromatic (DAC) perimetry as well as a novel clinical tool, scotopic chromatic pupil campimetry (CPC). The goal of the study was to explore the applicability of these methods in a clinical setting, their test-retest repeatability, and the congruence of the results. Local rod sensitivity was assessed at 36 locations within 30° eccentricity of the visual field in 15 healthy subjects (mean age 43 ± 16 years; 7 females and 8 males) with DAC perimetry (red and cyan stimuli) and CPC 2 times in repeated measurements.

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To call attention to the danger of extinction of the panda bear, the Lithuanian artist Ilja Klemencov created the artwork "They can disappear". The illustration is composed of black-and-white zigzagged lines, which form the famous panda logo of the World Wild Fund For Nature (WWF) when seen from a distance. If one is too close to the artwork, it is difficult to spot the bear, however, if one steps back or takes off one's glasses the panda suddenly appears.

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Presbyopia and myopia research shows a growing interest in ciliary muscle biometry using optical coherence tomography (OCT). Until now, segmentation of the ciliary muscle is often performed manually using either custom-developed programs or image processing software. Here we present a novel software for semi-automatic segmentation of the ciliary muscle.

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