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    Unaltered perception of suprathreshold contrast in early glaucoma despite sensitivity loss

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    Denniss_iovs_Final.pdf (831.1Kb)
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    Publication date
    2020-07
    Author
    Bham, H.A.
    Dewsbery, S.D.
    Denniss, Jonathan
    Keyword
    Glaucoma
    Contrast perception
    Contrast matching
    Contrast constancy
    Suprathreshold
    Research Development Fund Publication Prize Award
    Rights
    Copyright 2020 The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
    Peer-Reviewed
    Yes
    
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    Abstract
    PURPOSE. Glaucoma raises contrast detection thresholds, but our natural visual environment is dominated by high contrast that may remain suprathreshold in early to moderate glaucoma. This study investigates the effect of glaucoma on the apparent contrast of visible stimuli. METHODS. Twenty participants with glaucoma with partial visual field defects (mean age, 72 ± 7 years) and 20 age-similar healthy controls (mean age, 70 ± 7 years) took part. Contrast detection thresholds for Gabor stimuli (SD, 0.75°) of four spatial frequencies (0.5, 1.0, 2.0, and 4.0 c/deg) were first measured at 10° eccentricity, both within and outside of visual field defects for participants with glaucoma. Subsequently, the contrast of a central Gabor was matched to that of a peripheral Gabor with contrast fixed at two times or four times the detection threshold. Data were analyzed by linear mixed modelling. RESULTS. Compared with controls, detection thresholds for participants with glaucoma were raised by 0.05 ± 0.025 (Michelson units, ± SE; P = 0.12) and by 0.141 ± 0.026 (P < 0.001) outside and within visual field defects, respectively. For reference stimuli at two times the detection contrast, matched contrast ratios (matched/reference contrast) were 0.16 ± 0.039 (P < 0.001) higher outside compared with within visual field defects in participants with glaucoma. Matched contrast ratios within visual field defects were similar to controls (mean 0.033 ± 0.066 lower; P = 0.87). For reference stimuli at four times the detection contrast, matched contrast ratios were similar across all three groups (P = 0.58). Spatial frequency had a minimal effect on matched contrast ratios. CONCLUSIONS. Despite decreased contrast sensitivity, people with glaucoma perceive the contrast of visible suprathreshold stimuli similarly to healthy controls. These results suggest possible compensation for sensitivity loss in the visual system.
    URI
    http://hdl.handle.net/10454/17921
    Version
    Published version
    Citation
    Bham HA, Dewsbery SD and Denniss J (2020) Unaltered perception of suprathreshold contrast in early glaucoma despite sensitivity loss. Investigative Ophthalmology & Visual Science. 61(8): 23.
    Link to publisher’s version
    https://doi.org/10.1167/iovs.61.8.23
    Type
    Article
    Notes
    Research Development Fund Publication Prize Award winner, June 2020
    Collections
    Life Sciences Publications

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