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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Melanopsin‐expressing ganglion cells in human retina: Morphology, distribution, and synaptic connections

The Journal of Comparative Neurology, Journal Year: 2017, Volume and Issue: 527(1), P. 312 - 327

Published: Jan. 18, 2017

Abstract Melanopsin‐expressing retinal ganglion cells are intrinsically photosensitive that involved in non‐image forming visual processes such as the pupillary light reflex and circadian entrainment but also contribute to perception. Here we used immunohistochemistry study morphology, density, distribution, synaptic connectivity of melanopsin‐expressing four post mortem human donor retinas. Two types were distinguished based on their dendritic stratification near either outer or inner border plexiform layer. Outer stratifying make up average 60% cells. About half (or 80% cells) have soma displaced nuclear Inner exclusively cell layer include a small proportion bistratified The field diameter ranges from 250 (near fovea) 1,000 µm peripheral retina. trees cover retina independent location. fields both show high degree overlap with coverage factor approximately two. occur at an peak density between ∼20 ∼40 cells/mm 2 about mm eccentricity, drops below ∼10 8 eccentricity. Both dendrites express postsynaptic (PSD95) immunoreactive puncta suggesting they receive input bipolar

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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Retinal Ganglion Cells—Diversity of Cell Types and Clinical Relevance

Frontiers in Neurology, Journal Year: 2021, Volume and Issue: 12

Published: May 21, 2021

Retinal ganglion cells (RGCs) are the bridging neurons that connect retinal input to visual processing centres within central nervous system. There is a remarkable diversity of RGCs and various subtypes have unique morphological features, distinct functions, characteristic pathways linking inner retina relevant brain areas. A number psychophysical electrophysiological tests been refined investigate this large varied population RGCs. Technological advances, such as high-resolution optical coherence tomography imaging, provided additional tools define pattern RGC involvement chronological sequence events in both inherited acquired optic neuropathies. The mechanistic insights gained from these studies, particular selective vulnerability relative resilience subtypes, fundamental importance they directly development targeted therapies for invariably progressive blinding diseases. This review provides comprehensive description types RGCs, developments proposed methods classification, current gaps our knowledge how differentially affected depending on underlying aetiology. synthesis body potentially amenable therapeutic modulation will hopefully lead much needed effective treatments patients with

Language: Английский

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The value of visual field testing in the era of advanced imaging: clinical and psychophysical perspectives

Clinical and Experimental Optometry, Journal Year: 2017, Volume and Issue: 100(4), P. 313 - 332

Published: June 22, 2017

White-on-white standard automated perimetry (SAP) is widely used in clinical and research settings for assessment of contrast sensitivity using incremental light stimuli across the visual field. It one main functional measures effect disease upon system. SAP has evolved over last 40 years to become an indispensable tool comprehensive function. In modern practice, a range objective measurements ocular structure, such as optical coherence tomography, have also invaluable additions arsenal ophthalmic examination. Although structure-function correlation highly desirable determinant unambiguous picture patient, clinicians are often faced with discordance structural results, which presents them challenge. The construction principles behind development discuss interpretation fields, well problem discordance. Through illustrative examples, we provide useful insights assist combining results obtained from advanced imaging techniques into coherent that can help direct management.

Language: Английский

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Static and dynamic pupillometry data of healthy individuals

Clinical and Experimental Optometry, Journal Year: 2018, Volume and Issue: 101(5), P. 659 - 665

Published: Jan. 22, 2018

This study sought to determine normative static and dynamic pupillometry data in different age groups a healthy population, investigate the effects of on pupillometric characteristics.Pupillometry measurements were undertaken 155 participants using an automatic quantitative system. Static undertaken; these included scotopic pupil diameter (PD), mesopic PD, low photopic PD high values. Dynamic undertaken, including resting diameter, amplitude contraction, latency duration velocity dilation, dilation dilation.Overall, 69 (44.5 per cent) male 86 (55.5 female, with mean 29.7 ± 17.8 years. Neither nor varied significantly between males females. Age was inversely moderately correlated each characteristics (p < 0.05). Resting values 0.001, r = -0.63; p -0.47; -0.34, respectively). Latency contraction positively 0.002, 0.29).The current presents population-specific effect pupillary characteristics.

Language: Английский

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Rhodopsin and Melanopsin Contributions to the Early Redilation Phase of the Post-Illumination Pupil Response (PIPR)

PLoS ONE, Journal Year: 2016, Volume and Issue: 11(8), P. e0161175 - e0161175

Published: Aug. 22, 2016

Melanopsin expressing intrinsically photosensitive Retinal Ganglion Cells (ipRGCs) entirely control the post-illumination pupil response (PIPR) from 6 s post-stimulus to plateau during redilation after light offset. However, photoreceptor contributions early phase of PIPR (< post-stimulus) have not been reported. Here, we evaluated (0.6 5.0 s) by measuring spectral sensitivity criterion amplitude in 1 pulses at five narrowband stimulus wavelengths (409, 464, 508, 531 and 592 nm). The retinal irradiance producing a was normalised peak fitted either single photopigment nomogram or combined melanopsin rhodopsin nomograms with +L+M cone photopic luminous efficiency (Vλ) function. We show that times ≥ 1.7 offset is best described nomogram. At < s, shifts longer (range: 482 498 nm) nomogram, major rhodopsin. This first report line electrophysiological findings ipRGC rod signalling cessation stimuli provides cut-off time for isolating specific function healthy diseased eyes.

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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Photoreceptor contributions to the human pupil light reflex

Journal of Photochemistry and Photobiology, Journal Year: 2023, Volume and Issue: 15, P. 100178 - 100178

Published: April 2, 2023

The pupil reacts to the amount of light reaching eye. It reduces its size when is high and dilates at low levels allow entrance more photons. This behavior called reflex (PLR). Recent investigations in humans were conducted understand how photoreceptor signals are combined drive reflex. review about physiological processes that govern humans. In particular, cone-opsins, rhodopsin, melanopsin photoreception contribute governing PLR. We also summarize on assessment PLR clinical settings.

Language: Английский

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Pupillary Responses to Full-Field Chromatic Stimuli Are Reduced in Patients with Early-Stage Primary Open-Angle Glaucoma

Ophthalmology, Journal Year: 2018, Volume and Issue: 125(9), P. 1362 - 1371

Published: March 21, 2018

To evaluate the ability of chromatic pupillometry to reveal abnormal pupillary responses light in patients with early-stage primary open-angle glaucoma (POAG) and test whether degree pupillometric impairment correlates structural hallmarks optic nerve damage disease.Cross-sectional study.Forty-six POAG (63.4±8.3 years, 63% male, 87% ethnic-Chinese) 90 age-matched healthy controls (61.4±8.6 34% 89% ethnic-Chinese). Patients had a visual field mean deviation (VFMD) -6 decibels or better on automated perimetry.Each participant underwent monocular 2-minute exposure blue (462 nm) followed by another red (638 using modified Ganzfeld dome equipped light-emitting diode lighting system. The stimuli intensity was increased logarithmically combined extrinsic intrinsic response intrinsically photosensitive retinal ganglion cells (ipRGCs). Light-induced changes horizontal pupil diameter were assessed monocularly infrared pupillography.Baseline-adjusted, light-induced constriction amplitudes calculated, individual irradiance-response curves constructed for each stimulus. Pupillary compared between groups across intensities linear mixed model analysis. relationship parameters different functional features Pearson's correlation analysis.Light-induced reduced at moderate high irradiances (≥11 Log photons/cm2/s) (P = 0.003) < 0.001) light. Maximal amplitude correlated fiber layer thickness (RNFL) (blue: r 0.51, P 0.001; red: 0.45, 0.002) but not controls. Conversely, scores POAG.Patients exhibit lights. This wavelength-independent alteration thinning RNFL could be consequence dysfunction loss melanopsin expressing ipRGCs early stages disease.

Language: Английский

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