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Human retinal dark adaptation tracked in vivo with the electroretinogram: insights into processes underlying recovery of cone- and rod-mediated vision.

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cam.issuedOnline2022-06-07
dc.contributor.authorJiang, Xiaofan
dc.contributor.authorMahroo, Omar A
dc.contributor.orcidMahroo, Omar A [0000-0003-1254-0832]
dc.date.accessioned2022-06-08T08:00:10Z
dc.date.available2022-06-08T08:00:10Z
dc.date.issued2022-11
dc.date.submitted2022-03-15
dc.date.updated2022-06-08T08:00:09Z
dc.descriptionFunder: Moorfields Eye Charity; Id: http://dx.doi.org/10.13039/501100017645
dc.description.abstractThe substantial time taken for regaining visual sensitivity (dark adaptation) following bleaching exposures has been investigated for over a century. Psychophysical studies yielded the classic biphasic curve representing recovery of cone-driven and rod-driven vision. The electroretinogram (ERG) permits direct assessment of recovery at the level of the retina (photoreceptors, bipolar cells), with the first report over 70 years ago. Over the last two decades, ERG studies of dark adaptation have generated insights into underlying physiological processes. After large bleaches, rod photoreceptor circulating current, estimated from the rod-isolated bright-flash ERG a-wave, takes 30 min to recover, indicating that products of bleaching, thought to be free opsin (unbound to 11-cis-retinal), continue to activate phototransduction, shutting off rod circulating current. In contrast, cone current, assessed with cone-driven bright-flash ERG a-waves, recovers within 100 ms following similar exposures, suggesting that free opsin is less able to shut off cone current. The cone-driven dim-flash a-wave can be used to track recovery of cone photopigment, showing regeneration is 'rate-limited' rather than first order. Recoveries of the dim-flash ERG b-wave are consistent also with rate-limited rod photopigment regeneration (where free opsin, desensitising the visual system as an 'equivalent background', is removed by rate-limited delivery of 11-cis-retinal). These findings agree with psychophysical and retinal densitometry studies, although there are unexplained points of divergence. Post-bleach ERG recovery has been explored in age-related macular degeneration and in trials of visual cycle inhibitors for retinal diseases. ERG tracking of dark adaptation may prove useful in future clinical contexts.
dc.identifier.doi10.17863/CAM.85306
dc.identifier.eissn1469-7793
dc.identifier.issn0022-3751
dc.identifier.othertjp15123
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/337900
dc.languageen
dc.language.isoeng
dc.publisherWiley
dc.publisher.urlhttp://dx.doi.org/10.1113/jp283105
dc.subjectcone photoreceptors
dc.subjectdark adaptation
dc.subjectelectroretinographyy
dc.subjectretina
dc.subjectretinal bipolar cells
dc.subjectrod photoreceptors
dc.subjectHumans
dc.subjectDark Adaptation
dc.subjectRetinaldehyde
dc.subjectRetinal Rod Photoreceptor Cells
dc.subjectPhotic Stimulation
dc.subjectElectroretinography
dc.subjectRetinal Cone Photoreceptor Cells
dc.subjectRetina
dc.subjectOpsins
dc.titleHuman retinal dark adaptation tracked in vivo with the electroretinogram: insights into processes underlying recovery of cone- and rod-mediated vision.
dc.typeArticle
dcterms.dateAccepted2022-05-04
prism.publicationNameJ Physiol
pubs.funder-project-idWellcome Trust (206619/Z/17/Z)
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/
rioxxterms.versionVoR
rioxxterms.versionofrecord10.1113/JP283105

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