Dataset Information

Unaltered Perception of Suprathreshold Contrast in Early Glaucoma Despite Sensitivity Loss.

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.

SUBMITTER: Bham HA

PROVIDER: S-EPMC7425759 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Unaltered Perception of Suprathreshold Contrast in Early Glaucoma Despite Sensitivity Loss.

Bham Habiba A HA Dewsbery Simon D SD Denniss Jonathan J

Investigative ophthalmology & visual science 20200701 8

<h4>Purpose</h4>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.<h4>Methods</h4>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 Gabo ...[more]

PMID: 32676636

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Project description:ImportanceFacial recognition is a critical activity of daily living that relies on macular function. Glaucomatous macular damage may result in impaired facial recognition that may negatively affect patient quality of life.ObjectiveTo evaluate the association of patterns of glaucomatous macular damage with contrast sensitivity and facial recognition among patients with glaucoma.Design, setting, and participantsIn this prospective cohort study at a single tertiary care center, 144 eyes of 72 consecutive patients with glaucoma with good visual acuity (20/40 or better in each eye) were studied. Data were collected from March to April 2019.ExposuresEyes with macular damage were categorized as having focal, diffuse, or mixed (focal and diffuse) damage based on optic disc and macular spectral-domain optical coherence tomography and 10-2 visual field (VF) damage. Only eyes with focal or diffuse damage were included. Higher-acuity and lower-acuity eyes were determined by 10-2 VF mean deviation (MD). Facial disability was defined as facial recognition scores at the 2% level of normal participants.Main outcomes and measures(1) Monocular contrast threshold as measured by the Freiburg Visual Acuity and Contrast Test and (2) binocular facial recognition as measured by the Cambridge Face Memory Test.ResultsOf the 72 included patients, 49 (68%) were White and 41 (57%) were female, and the mean (SD) age was 67.0 (11.6) years. Eyes with diffuse damage had greater contrast impairment compared with eyes with focal damage (β = -0.5; 95% CI, -0.6 to -0.4; P < .001) after adjusting for 10-2 VF MD, 24-2 VF MD, age, presence of an early cataract, and number of drops. Similarly, Cambridge Face Memory Test scores were significantly lower in patients with diffuse rather than focal macular damage, regardless of eye (better-seeing eye: β = 10.0; 95% CI, 2.0 to 18.2; P = .001; worse-seeing eye: β = 5.5; 95% CI, 0.8 to 10.0; P = .23). Relative risk of facial disability was greater for patients with diffuse but not focal macular damage in the better-seeing eye (relative risk, 86.2; 95% CI, 2.7 to 2783.3; P = .01).Conclusions and relevanceIn this cohort study, diffuse rather than focal glaucomatous macular damage was associated with diminished facial recognition and contrast sensitivity. Evaluation of macular optical coherence tomography and 10-2 VF and resultant detection of diffuse macular damage may help minimize glaucoma-related visual disability.

Dataset Information

Unaltered Perception of Suprathreshold Contrast in Early Glaucoma Despite Sensitivity Loss.

Publications

Unaltered Perception of Suprathreshold Contrast in Early Glaucoma Despite Sensitivity Loss.

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