Retinal vessel reaction in response to chromatic flickering light

Kotliar, Konstantin; Vilser, Walthard; Nagel, Edgar; Lanzl, Ines

doi:10.1007/s00417-003-0847-x

Cited by 62 publications

(43 citation statements)

References 21 publications

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“…results confirm previous observations in humans 15 and animals 22 that most of the arterial dilation occurs within the first 10 seconds of stimulation. Additionally no significant increase in maximum dilation was found in arteries between flicker durations of 5, 7, 10, and 20 seconds.…”

Section: Effect Of Flicker Duration On Retinal Vessel Dilationsupporting

confidence: 82%

“…Although there has been prior research aimed at determining the best FL frequency, 13 effects of illumination, 15 and some comparison between two flicker durations 15 there has, as far as we know, been no systematic effort made to examine the effects of shorter FL durations and hence the time-course of retinal vessel dilation and constriction due to FL provocation as a function of FL duration.…”

Section: Effect Of Flicker Duration On Retinal Vessel Dilationmentioning

confidence: 99%

“…While some groups 1,14 use a 3-flicker-cycle protocol where each flicker cycle has a different duration (16,32, and 64 seconds) the flicker frequency (8 Hz) and method of flicker provocation (flicker is spectrally distinct from measurement illumination) make the results difficult to compare with those obtained with the standard protocol where the flicker is obtained by completely interrupting the illumination at 12.5 Hz and a single duration is measured in one setting. An early study 15 compared flicker durations of 10 and 30 seconds but the protocol for each flicker duration was different; for FL durations of 10 seconds five cycles of flicker were separated by 80 seconds of baseline measurements, whereas for durations of 30 seconds only three cycles were measured and each cycle was separated by 120 seconds. Analysis was carried out on the vessel diameters averaged over the flicker cycles (three or five).…”

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confidence: 99%

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The Time Course of Changes in Retinal Vessel Diameter in Response to Differing Durations of Flicker Light Provocation

Heitmar

Summers

2015

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To determine the response of retinal vessels to differing durations of flicker light (FL) stimulation. METHODS.We recorded retinal arterial and venous vessel dilation to 12.5 Hz FL provocation of varying duration (5, 7, 10, and 20 seconds) in 12 healthy young individuals (age range, 26-45 years). All participants underwent a full ocular examination including IOP and blood pressure measurements.RESULTS. Maximum dilation (MD) did not show a significant dependence on flicker duration in arteries, whereas maximum constriction (MC) did. In veins, however, MD significantly increased with flicker duration. Approximately 80% to 90% of MD in arteries is reached within 10 seconds of FL stimulation.CONCLUSIONS. The vast majority of arterial dilatory capacity is reached within 10 seconds of FL stimulation even though venous dilation continues strongly. Since MC of arteries shows a significant dependence on flicker duration, measurements at two different durations can provide more information about the retinal vascular system than at a single flicker duration alone.

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Section: Effect Of Flicker Duration On Retinal Vessel Dilationsupporting

confidence: 82%

Section: Effect Of Flicker Duration On Retinal Vessel Dilationmentioning

confidence: 99%

mentioning

confidence: 99%

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The Time Course of Changes in Retinal Vessel Diameter in Response to Differing Durations of Flicker Light Provocation

Heitmar

Summers

2015

Invest. Ophthalmol. Vis. Sci.

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“…[44][45][46] Regarding the localized nature of SVP, while many reports assumed a constant venous flow upstream to the SVP site, pulsation has been observed using various techniques. 45,[47][48][49][50] Clearly, the constancy of the pulsation waveform along primary veins requires further study. We found that waveforms differ markedly between subjects; hence, a higher temporal resolution for better characterization should be sought in future investigations.…”

Section: Limitationsmentioning

confidence: 99%

Quantitative Analysis of Fundus-Image Sequences Reveals Phase of Spontaneous Venous Pulsations

Moret

Reiff

Lagrèze

et al. 2015

Trans. Vis. Sci. Tech.

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Purpose: Spontaneous venous pulsation correlates negatively with elevated intracranial pressure and papilledema, and it relates to glaucoma. Yet, its etiology remains unclear. A key element to elucidate its underlying mechanism is the time at which collapse occurs with respect to the heart cycle, but previous reports are contradictory. We assessed this question in healthy subjects using quantitative measurements of both vein diameters and artery lateral displacements; the latter being used as the marker of the ocular systole time.Methods: We recorded 5-second fundus sequences with a near-infrared scanning laser ophthalmoscope in 12 young healthy subjects. The image sequences were coregistered, cleaned from microsaccades, and filtered via a principal component analysis to remove nonpulsatile dynamic features. Time courses of arterial lateral displacement and of diameter at sites of spontaneous venous pulsation or proximal to the disk were retrieved from those image sequences and compared.Results: Four subjects displayed both arterial and venous pulsatile waveforms. On those, we observed venous diameter waveforms differing markedly among the subjects, ranging from a waveform matching the typical intraocular pressure waveform to a close replica of the arterial waveform. Conclusions:The heterogeneity in waveforms and arteriovenous phases suggests that the mechanism governing the venous outflow resistance differs among healthy subjects.Translational relevance: Further characterizations are necessary to understand the heterogeneous mechanisms governing the venous outflow resistance as this resistance is altered in glaucoma and is instrumental when monitoring intracranial hypertension based on fundus observations.

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“…[8][9][10] Most of the published data rely on the observation of vascular caliber variations to draw conclusions from vessel diameter changes on flow changes. [11][12][13][14] Typically, the diameter of a vessel is assessed by fundus photographic techniques, which allow for the real time evaluation of retinal vessel diameter. A large number of studies have been performed to assess vessel diameter changes during stimulation with diffuse luminance flicker in healthy subjects under normal conditions 9,11 or during oxygen breathing, 15 as well as in patients with diabetes, 16,17 glaucoma, 18,19 or systemic hypertension.…”

mentioning

confidence: 99%

Effect of Diffuse Luminance Flicker Light Stimulation on Total Retinal Blood Flow Assessed With Dual-Beam Bidirectional Doppler OCT

Aschinger

Schmetterer

Fondi

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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METHODS. In six healthy subjects, TRBF was measured before and during stimulation with diffuse luminance flicker. Blood flow velocities in retinal vessels were measured via dual-beam bidirectional Doppler Fourier-domain optical coherence tomography (FD-OCT), retinal vessel diameters were assessed based on FD-OCT phase data. This allowed for the calculation of TRBF before and during visual stimulation. Additionally, a mathematical flow model for the retinal vasculature was adapted to study the implications of diameter variations on retinal perfusion. Measured and simulated perfusion was compared to draw conclusions on the diameter variations in different layers of the vascular tree.RESULTS. The measured mean baseline flow was 36.4 6 6.5 ll/min while the mean flow during flicker stimulation was 53.4% 6 8.3 ll/min. The individual increase in TRBF during flicker stimulation ranged between 34% and 66%. The average increase in TRBF over all measured subjects was 47.6% 6 12.6%.CONCLUSIONS. Dual-beam bidirectional Doppler FD-OCT allowed quantifying NC in the human retina in vivo and may be a promising method for monitoring alterations in NC caused by various pathologies. The comparison of the measured data with the results obtained in the simulated vasculature indicates that the vasodilation induced by NC is more pronounced in smaller vessels.

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Retinal vessel reaction in response to chromatic flickering light

Cited by 62 publications

References 21 publications

The Time Course of Changes in Retinal Vessel Diameter in Response to Differing Durations of Flicker Light Provocation

The Time Course of Changes in Retinal Vessel Diameter in Response to Differing Durations of Flicker Light Provocation

Quantitative Analysis of Fundus-Image Sequences Reveals Phase of Spontaneous Venous Pulsations

Effect of Diffuse Luminance Flicker Light Stimulation on Total Retinal Blood Flow Assessed With Dual-Beam Bidirectional Doppler OCT

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