Functional optical coherence tomography of neurovascular coupling interactions in the retina

Son, Taeyoon; Alam, Minhaj Nur; Toslak, Devrim; Wang, Benquan; Lu, Yiming; Yao, Xincheng

doi:10.1002/jbio.201800089

Cited by 30 publications

(36 citation statements)

References 51 publications

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“…These studies showed variations in response depending on the stimulus conditions, consistent with what is known of retinal visual processing 7 . In rodents similar results are found with flicker-evoked increases in flow in both mice, using optical coherence tomography angiography 8,9 and rats, using fluorescein angiography 10 . For humans neurovascular coupling has been intensively investigated in the brain 11,12 , where it is the source of the BOLD signal that underlies fMRI 13 as well as in the retina using noninvasive imaging.…”

supporting

confidence: 78%

Full-field flicker evoked changes in parafoveal retinal blood flow

Warner

Castro

Sawides

et al. 2020

Sci Rep

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When retinal activity is increased by exposure to dynamic visual stimuli, blood vessels dilate and the flow of blood within vessels increases to meet the oxygen and glucose demands of the neurons. This relationship is termed ‘neurovascular coupling’ and it is critical for regulating control of the human retinal vasculature. In this study, we used a recently developed technique based on a dual-beam adaptive optics scanning laser ophthalmoscope to measure changes in red blood cell velocities, vessel diameter, and flow in interconnected small parafoveal retinal vessels (< 50 µm) of nine healthy participants. A full-field flicker stimulus was presented onto the retina to induce a vascular response to neural activity. Flicker stimulation increased blood velocity, vessel diameter, and therefore flow in arterioles, capillaries, and venules in all nine subjects. ANOVA and post hoc t-test showed significant increases in velocity and flow in arterioles and venules. These measurements indicate that the mechanism of neurovascular coupling systematically affects the vascular response in small retinal vessels in order to maintain hemodynamic regulation in the retina when exposed to visual stimulation, in our case flicker. Our findings may provide insight into future investigations on the impairments of neurovascular coupling from vascular diseases such as diabetic mellitus.

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confidence: 78%

Full-field flicker evoked changes in parafoveal retinal blood flow

Warner

Castro

Sawides

et al. 2020

Sci Rep

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“…33 IOS imaging of laser-injured frog eyes demonstrated that the confocal IOS can clearly detect localized (30 mm) functional lesions in the retina before morphological abnormality is detectable. 53 Depth-resolved in vivo OCT imaging of stimulus-evoked IOS changes in frog 58 and mouse 30,57 retinas further showed that the fast IOS changes were primarily observed at the photoreceptor layer, particularly the OS region. With increased stimulus duration or repeated flash stimuli, IOS changes were also detected in the inner retinal layers.…”

Section: In Vitro Imaging Of Photoreceptor-iosmentioning

confidence: 97%

“…A recent comparative study of wild-type (WT) and retinal degeneration 10 (rd10) mice demonstrated that fast photoreceptor-IOS occurs even earlier than PDE activation. 46 In vivo imaging of photoreceptor-IOS Modified fundus camera, [47][48][49][50] adaptive optics, 51,52 confocal, 53,54 and OCT 30,[55][56][57][58][59][60][61] systems have been explored for in vivo retinal IOS imaging of anesthetized animals 30,[47][48][49][50]53,54,[57][58][59] and awake humans. 51,52,55,60,61 A high-speed (200 frames/s) line-scan confocal ophthalmoscope has been used to demonstrate in vivo IOS imaging of intact frog eyes.…”

Section: In Vitro Imaging Of Photoreceptor-iosmentioning

confidence: 99%

Fast intrinsic optical signal correlates with activation phase of phototransduction in retinal photoreceptors

Yao

Kim

2020

Exp Biol Med (Maywood)

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Quantitative assessment of physiological condition of retinal photoreceptors is desirable for better detection and treatment evaluation of eye diseases that can cause photoreceptor dysfunctions. Functional intrinsic optical signal (IOS) imaging, also termed as optoretinography (ORG) or optophysiology, has been proposed as a high-resolution method for objective assessment of retinal physiology. Fast IOS in retinal photoreceptors shows a time course earlier than that of electroretinography a-wave, promising an objective marker for noninvasive ORG of early phototransduction process in retinal photoreceptors. In this article, recent observations of fast photoreceptor-IOS in animal and human retinas are summarized, and the correlation of fast photoreceptor-IOS to five steps of phototransduction process is discussed. Transient outer segment conformational change, due to inter-disc space shrinkage correlated with activation phase of phototransduction, has been disclosed as a primary source of the fast photoreceptor-IOS. Impact statement As the center of phototransduction, retinal photoreceptors are responsible for capturing and converting photon energy to bioelectric signals for following visual information processing in the retina. This article summarizes experimental observation and discusses biophysical mechanism of fast photoreceptor-intrinsic optical signal (IOS) correlated with early phase of phototransduction. Quantitative imaging of fast photoreceptor-IOS may provide objective optoretinography to advance the study and diagnosis of age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and other eye diseases that can cause photoreceptor dysfunctions.

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“…With the 10-ms visible light flash stimulation, the IOS changes were primarily observed at the photoreceptor layer, particularly the outer segment (Figure 6(e) and (f)). With increased stimulus duration, 24 or repeated flash stimuli, 27 i.e. flicker stimulation, stimulusevoked IOS changes were also observed in inner retinal layers.…”

Section: Functional Oct Imaging Of Retinal Activationmentioning

confidence: 99%

“…Scale bars in (a1) and (b1) indicate 500 mm. Modified with permission from Son et al27 (A color version of this figure is available in the online journal. )…”

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confidence: 99%

Functional optical coherence tomography of retinal photoreceptors

Yao

Son

Kim

et al. 2018

Exp Biol Med (Maywood)

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Age-related macular degeneration (AMD) is the leading cause of severe vision loss and legal blindness. It is known that retinal photoreceptors are the primary target of AMD. Therefore, a reliable method for objective assessment of photoreceptor function is needed for early detection and reliable treatment evaluation of AMD and other eye diseases such as retinitis pigmentosa that are known to cause photoreceptor dysfunctions. Stimulus-evoked intrinsic optical signal (IOS) changes promise a unique opportunity for objective assessment of physiological function of retinal photoreceptor and inner neurons. Instead of a comprehensive review, this mini-review is to provide a brief summary of our recent in vitro and in vivo optical coherence tomography (OCT) studies of stimulus-evoked IOS changes in animal retinas. By providing excellent axial resolution to differentiate individual retinal layers, depth-resolved OCT revealed rapid IOS response at the photoreceptor outer segment. The fast photoreceptor-IOS occurred almost right away (∼ 2 ms) after the onset of retinal stimulation, differentiating itself from slow IOS changes correlated with inner neural and hemodynamic changes. Further development of the functional IOS instruments and retinal stimulation protocols may provide a feasible solution to pursue clinical application of functional IOS imaging for objective assessment of human photoreceptors. Impact statement Retinal photoreceptors are the primary target of age-related macular degeneration (AMD) which is the leading cause of severe vision loss and legal blindness. An objective method for functional assessment of photoreceptor physiology can benefit early detection and better treatment evaluation of AMD and other eye diseases that are known to cause photoreceptor dysfunctions. This article summarizes in vitro study of IOS mechanisms and in vivo demonstration of IOS imaging of intact animals. Further development of the functional IOS imaging may provide a revolutionary solution to achieve objective assessment of human photoreceptors.

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Functional optical coherence tomography of neurovascular coupling interactions in the retina

Cited by 30 publications

References 51 publications

Full-field flicker evoked changes in parafoveal retinal blood flow

Full-field flicker evoked changes in parafoveal retinal blood flow

Fast intrinsic optical signal correlates with activation phase of phototransduction in retinal photoreceptors

Functional optical coherence tomography of retinal photoreceptors

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