Rapid Contrast Adaptation in Glaucoma and in Aging

Lek, Jia Jia; Vingrys, Algis J.; McKendrick, Allison M

doi:10.1167/iovs.13-13229

Cited by 18 publications

(12 citation statements)

References 46 publications

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“…Additionally, as previously noted, care needs to be taken in interpreting PVEP signals as its contributions are not limited to V1. 18,57,63 In this study, glaucoma participants demonstrated flatter retinal contrast response functions, a finding consistent with elevated contrast discrimination thresholds 14,28,67 and reduced contrast gain signatures found in perceptual studies. [14][15][16] The PERG magnitude loss (~52%) in our early glaucoma cohort was of a similar extent as compared to previous studies, 41,42,68,69 and is likely due to retinal ganglion cell loss 7 or dysfunction 70,71 in glaucoma.…”

Section: Discussionsupporting

confidence: 87%

“…23 Studies in older adults have shown that aging can result in neurological alterations at the retina including the loss of retinal ganglion cells, 24,25 as well as at the LGN 26 and visual cortex, 27 the same sites that undergo neurodegeneration in glaucoma. Healthy aging alters a range of perceptual contrast effects, including contrast detection, 28,29 contrast discrimination, 28 spatial contrast suppression 30,31 and contrast gain signatures. 32 Such perceptual effects are consistent with changes to both structural and neurochemical changes in the senescent visual system (for review, see McKendrick et al 33 ) In many ophthalmic conditions, the effects of aging and the effects of disease appear along a continuum.…”

mentioning

confidence: 99%

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An Electrophysiological Comparison of Contrast Response Functions in Younger and Older Adults, and Those With Glaucoma

Lek

Nguyen

McKendrick

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Aging and glaucoma both result in contrast processing deficits. However, it is unclear the extent to which these functional deficits arise from retinal or post-retinal neuronal changes. This study aims to disentangle the effects of healthy human aging and glaucoma on retinal and post-retinal contrast processing using visual electrophysiology. METHODS. Steady-state pattern electroretinograms (PERG) and pattern visual evoked potentials (PVEP) were simultaneously recorded across a range of contrasts (0%, 4%, 9%, 18%, 39%, 73%, 97%; 0.88 diameter checks, 318 diameter checkerboard) in 13 glaucoma patients (67 6 6 years), 15 older (63 6 8 years) and 14 younger adults (27 6 3 years). PERG and PVEP contrast response functions were fit with a linear and saturating hyperbolic model, respectively. PERG and PVEP magnitude, timing (phase), and model fit parameters (slope, semi-saturation constant) were compared between groups. RESULTS. PERG responses were reduced and delayed in older adults relative to younger adults, and further reduced and delayed in glaucoma patients across all contrasts. PVEP signals were also reduced and delayed in glaucoma patients, relative to age-similar (older) controls. However, despite having reduced PERG magnitudes, older adults did not demonstrate reduced PVEP magnitudes. CONCLUSIONS. Older adults with healthy vision demonstrate reduced magnitude and delayed timing in the PERG that is not reflected in the PVEP. In contrast, glaucoma produces functional deficits in both PERG and PVEP contrast response functions. Our results suggest that glaucomatous effects on contrast processing are not a simple extension of those that arise as part of the aging process.

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Section: Discussionsupporting

confidence: 87%

mentioning

confidence: 99%

An Electrophysiological Comparison of Contrast Response Functions in Younger and Older Adults, and Those With Glaucoma

Lek

Nguyen

McKendrick

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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“…Very few studies have investigated these aspects of visual function in older adults. Current available data suggests that rapid contrast adaptation is similar between age groups for briefly presented grating stimuli . The question of whether slow contrast adaptation differs between older and younger people does not appear to have been tested directly, however, performance measured in older adults appears at least qualitatively similar to separate reports collected in younger adults …”

Section: The Ageing Eyementioning

confidence: 93%

Spatial vision in older adults: perceptual changes and neural bases

McKendrick

Chan

Nguyen

2018

Ophthalmic Physiologic Optic

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Healthy normal ageing impacts significantly on spatial visual information processing from the retina through to visual cortex. Some human data validates that obtained from studies of animal physiology, however some findings indicate that rethinking of presumed neural substrates is required. Notably, not all spatial visual processes are altered by age. Healthy normal ageing impacts significantly on some spatial visual processes (in particular centre-surround tasks), but leaves contrast discrimination, contrast adaptation, and orientation discrimination relatively intact. The study of older adult vision contributes to knowledge of the brain mechanisms altered by the ageing process, can provide practical information regarding visual environments that older adults may find challenging, and may lead to new methods of assessing visual performance in clinical environments.

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“…Glaucoma was associated with a reduction in contrast detection and discrimination adaptation in the early stages. 27 Reduction of visual acuity or contrast sensitivity caused slower reading speed in glaucoma. 28 Our findings might suggest that reading speed reduction in the early stages of glaucoma might be just transient evidence of coping mechanisms being established.…”

Section: Discussionmentioning

confidence: 99%

The impact of glaucomatous visual field defects on speed and eye movements during reading

Chen

2020

Smj

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Objective: To investigate the link between glaucomatous visual field defects and reading performance by assessing reading speed and eye movements in reading. Methods: Eight glaucoma patients and 8 normal-sighted participants were recruited using convenience sampling in this cross-sectional study. The visual field was evaluated using the Humphrey Matrix 24-2. Reading speed was assessed in words per minute using Buari-Chen Malay Reading Chart and the SAH reading passages compendium. Eye movements in reading were recorded using 3D video-oculography. Results: Glaucoma and control groups displayed significant differences in reading speed (t=3.12; p<0.05) and fixation (t=-2.59; p<0.05). Reading speed was significantly correlated with the total defect areas (r =+0.62, p<0.05) and the types of glaucomatous field defects (Analysis of Variance, ANOVA: F =4.65, p<0.05). No correlation was apparent in eye movements (p>0.05). Conclusion:The association of defect areas and types with reading speed but not with eye movements might suggest a different coping strategy between eye movement adjustment and reading adaptation in response to visual field defects. Significant association with fixation but not with saccades might indicate that the disengaged and engaged mechanisms of visual attention are affected differently by visual field defects.

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Rapid Contrast Adaptation in Glaucoma and in Aging

Abstract: Glaucoma alters rapid contrast adaptation while aging does not. Contrast adaptation is key to visual processing in natural visual environments. Our results imply that glaucoma produces abnormalities in natural visual experiences in central vision.

Cited by 18 publications

References 46 publications

An Electrophysiological Comparison of Contrast Response Functions in Younger and Older Adults, and Those With Glaucoma

An Electrophysiological Comparison of Contrast Response Functions in Younger and Older Adults, and Those With Glaucoma

Spatial vision in older adults: perceptual changes and neural bases

The impact of glaucomatous visual field defects on speed and eye movements during reading

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