Standards in Pupillography

Frontiers in Neurology, Journal Year: 2019, Volume and Issue: 10

Published: Feb. 21, 2019

The number of research groups studying the pupil is increasing, as publications. Consequently, new standards in pupillography are needed to formalize methodology including recording conditions, stimulus characteristics, well suitable parameters evaluation. Since description intrinsically photosensitive retinal ganglion cells (ipRGCs) there has been an increased interest and broader application ophthalmology other fields psychology chronobiology. Colour plays important role not only but also clinical observational therapy studies like gene hereditary degenerations psychopathology. Stimuli can vary size, brightness, duration, wavelength. Stimulus paradigms determine whether rhodopsin-driven rod responses, opsin-driven cone or melanopsin-driven ipRGC responses primarily elicited. Background illumination, adaptation state, instruction for participants will furthermore influence results. This standard recommends a minimum set variables be used specified publication methodologies. Initiated at 32nd International Pupil Colloquium 2017 Morges, Switzerland, aim this manuscript outline based on current knowledge experience experts order achieve greater comparability pupillographic studies. Such particularly facilitate proper by researchers field. First we describe general standards, followed specific suggestions concerning demands different targets research: afferent efferent reflex arc, pharmacology, psychology, sleepiness-related animal

Language: Английский

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Light-Induced Pupillary Responses in Alzheimer's Disease

Frontiers in Neurology, Journal Year: 2019, Volume and Issue: 10

Published: April 12, 2019

The impact of Alzheimer's disease (AD) on the pupillary light response (PLR) is controversial, being dependent stage and experimental pupillometric protocols. main hypothesis driving pupillometry research in AD based concept that AD-related neurodegeneration affects both parasympathetic sympathetic arms PLR (cholinergic noradrenergic theory), combined with additional alterations afferent limb, involving melanopsin expressing retinal ganglion cells (mRGCs), subserving PLR. Only a few studies have evaluated value as potential biomarker AD, providing various results compatible dysfunction, displaying increased latency constriction to light, decreased amplitude, faster redilation after offset, maximum velocity (MCV) acceleration (MCA) compared controls. Decreased MCV MCA appeared be most accurate all parameters allowing differentiation between healthy controls while post-illumination was consistent feature, however, these could not replicated by more recent studies, focusing early pre-clinical stages disease. Whether static or dynamic yields useful biomarkers for screening diagnosis remains unclear. In this review, we synopsize current knowledge features other neurodegenerative diseases, discuss roles detection, monitoring, alone combination biomarkers.

Language: Английский

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Chromatic Pupillometry Methods for Assessing Photoreceptor Health in Retinal and Optic Nerve Diseases

Frontiers in Neurology, Journal Year: 2019, Volume and Issue: 10

Published: Feb. 12, 2019

The pupillary light reflex is mediated by melanopsin-containing intrinsically-photosensitive retinal ganglion cells (ipRGCs), which also receive input from rods and cones. Melanopsin-dependent responses are short-wavelength sensitive, have a higher threshold of activation, much slower to activate de-activate compared with rod/cone-mediated responses. Given that rod/cone photoreceptors melanopsin differ in their response properties, stimuli can be designed stimulate preferentially each the different photoreceptor types, providing read-out function. This has given rise chromatic pupillometry methods aim assess health outer ipRGCs measuring blue or red stimuli. Here, we review types protocols been tested patients optic nerve disease, including approaches use short-duration exposures continuous exposure light. Across protocols, disease (e.g., retinitis pigmentosa Leber congenital amaurosis) show reduced absent dim blue-light used rod function, moderately-bright red-light cone By comparison, glaucoma ischemic neuropathy, but not mitochondrial disease) impaired during bright stimuli, post-illumination after offset, These proof-of-concept studies demonstrate damage ipRGCs. In future studies, it will important determine whether for screening early detection diseases. Such may prove useful objectively evaluating degree recovery ipRGC function blind who undergo gene therapy other treatments restore vision.

Language: Английский

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iPhone-based Pupillometry: A Novel Approach for Assessing the Pupillary Light Reflex

Optometry and Vision Science, Journal Year: 2018, Volume and Issue: 95(10), P. 953 - 958

Published: Oct. 1, 2018

SIGNIFICANCE The response of the pupil to a flash light, pupillary light reflex (PLR), is an important measure in optometry and other fields medicine that typically evaluated by qualitative observation. Here we describe simple, portable, iPhone-based pupillometer quantifies PLR real time. PURPOSES purposes this study were novel application records compare its technical capabilities with laboratory-based infrared (IR) camera system. METHODS Pupil sizes measured from 15 visually normal subjects (age, 19 65 years) using IR system Sensitometer test. This test elicits constriction iPhone flash, size camera, provides measurements Simultaneous recordings obtained two measures calculated: (1) dark-adapted steady-state (2) minimum after flash. was defined as difference between these measures. also recorded during redilation phase Bland-Altman analysis used assess limits agreement methods. RESULTS Statistically significant correlations found for (r = 0.91, P < .001) 0.65, .03). indicated mean 6% limit 14%, indicating 95% are expected have differ 14% or less. 1% methods; 5%. CONCLUSIONS There excellent responses camera. highly promising approach inexpensive measurements.

Language: Английский

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Cone Photoreceptor Dysfunction in Early-Stage Diabetic Retinopathy: Association Between the Activation Phase of Cone Phototransduction and the Flicker Electroretinogram

Investigative Ophthalmology & Visual Science, Journal Year: 2019, Volume and Issue: 60(1), P. 64 - 64

Published: Jan. 14, 2019

Purpose: To define the nature and extent of cone photoreceptor abnormalities in diabetic individuals who have mild or no retinopathy by assessing activation phase phototransduction flicker ERG these individuals. Methods: Light-adapted single-flash ERGs were recorded from 20 clinically apparent (NDR), nonproliferative (NPDR), nondiabetic, age-equivalent controls. A-waves elicited flashes different retinal illuminance fit with a delayed Gaussian model to derive Rmp3 (maximum amplitude massed response) S (phototransduction sensitivity). Fundamental full-field sinusoidal obtained across frequency range 6 100 Hz. Results: ANVOA indicated that both groups had significant losses compared controls, whereas mean did not differ significantly among groups. ANOVA also reduced for frequencies ≥56 Hz Flicker timing (phase) Log + log was correlated patients' high-frequency (62.5 Hz) loss (r = 0.69, P < 0.001). Conclusions: The a-wave is useful characterizing can help explain early-stage retinopathy. Reduced sensitivity attenuated provide evidence impaired function

Language: Английский

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Dysregulated 24 h melatonin secretion associated with intrinsically photosensitive retinal ganglion cell function in diabetic retinopathy: a cross-sectional study

Diabetologia, Journal Year: 2024, Volume and Issue: 67(6), P. 1114 - 1121

Published: Feb. 27, 2024

Language: Английский

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Pupillary light reflex as a diagnostic aid from computational viewpoint: A systematic literature review

Journal of Biomedical Informatics, Journal Year: 2021, Volume and Issue: 117, P. 103757 - 103757

Published: April 4, 2021

Language: Английский

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Melanopsin photoreception differentially modulates rod-mediated and cone-mediated human temporal vision

iScience, Journal Year: 2022, Volume and Issue: 25(7), P. 104529 - 104529

Published: June 3, 2022

To evaluate the nature of interactions between visual pathways transmitting slower melanopsin and faster rod cone signals, we implement a temporal phase summation paradigm in human observers using photoreceptor-directed stimuli. We show that stimulation interacts with alters both rod-mediated cone-mediated vision regardless whether it is perceptually visible or not. Melanopsin-rod result either inhibitory facilitatory depending on frequency photoreceptor pathway contrast sensitivity. Moreover, by isolating vision, reveal bipartite intensity response property photopic lighting extends its operational range at lower frequencies to beyond classic saturation limits but expense attenuating sensitivity higher frequencies. In comparison, melanopsin-cone always lead facilitation. These can be described linear probability summations potentially involve multiple intraretinal cortical set

Language: Английский

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Retinal neural dysfunction in diabetes revealed with handheld chromatic pupillometry

Clinical and Experimental Ophthalmology, Journal Year: 2022, Volume and Issue: 50(7), P. 745 - 756

Published: May 26, 2022

To evaluate the ability of handheld chromatic pupillometry to reveal and localise retinal neural dysfunction in diabetic patients with without retinopathy (DR).This cross-sectional study included 82 diabetics (DM) 93 controls (60.4 ± 8.4 years, 44.1% males). DM those (n = 25, 64.7 6.3 44.0% males) DR 57, 60.3 8.5 64.9% Changes horizontal pupil radius response blue (469 nm) red (640 light stimuli were assessed monocularly, clinics, using a custom-built pupillometer. Pupillometric parameters (phasic constriction amplitudes [predominantly from outer retina], maximal [from inner retina] post-illumination pupillary responses [PIPRs; predominantly retina]) extracted baseline-adjusted traces compared between controls, DR, DR. Net PIPR was defined as difference PIPRs.Phasic lights decreased (p < 0.001; p 0.001). Maximal 0.02), 0.005). both 0.02; 0.03), suggesting wavelength-dependent (and hence retinal) pupillometric or DR.Handheld can diabetes, even Patients but no displayed primarily dysfunction, while showed dysfunction.

Language: Английский

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Assessment of diurnal melatonin, cortisol, activity, and sleep−wake cycle in patients with and without diabetic retinopathy

Sleep Medicine, Journal Year: 2018, Volume and Issue: 54, P. 35 - 42

Published: Oct. 31, 2018

Language: Английский

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