Effect of stimulus configuration on crowding in strabismic amblyopia

Norgett, Yvonne; Siderov, John

doi:10.1167/17.13.5

Cited by 7 publications

(3 citation statements)

References 73 publications

(99 reference statements)

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“…Crowding also can occur in central vision, such as in strabismic amblyopia, a pathology characterized by reduced contrast sensitivity and strong foveal crowding. 41,42 The mechanisms underlying crowding are not yet well understood. Some accounts propose feature pooling, 43,44 grouping, 45 feature averaging, 43 changes in appearance, 39 limits of attentional resolution, 46 or tuning selectivity.…”

Section: Discussionmentioning

confidence: 99%

Glaucoma Affects Viewing Distance for Recognition of Sex and Facial Expression

Schafer

Rouland

Peyrin

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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Citation: Schafer A, Rouland JF, Peyrin C, Szaffarczyk S, Boucart M. Glaucoma affects viewing distance for recognition of sex and facial expression. Invest Ophthalmol Vis Sci. 2018;59:4921-4928. https://doi.org/ 10.1167/iovs.18-24875 PURPOSE. To measure the distance for sex and facial expression recognition in patients with glaucoma. METHODS.Sixteen patients with open-angle glaucoma, 16 age-matched controls, and 12 young controls participated. During each trial, a face covering 0.368 3 0.58, simulating the angular size of a face viewed at 20 m, was presented centrally. The angular size increased automatically by steps of 5 cm, simulating the face moving progressively closer. The participants were asked to stop the progression with a keypress, first, when they were able to recognize the sex, and second, when they were able to recognize the facial expression (angry, happy, neutral). We measured the threshold equivalent viewing distance to recognize the sex and the facial expression. RESULTS.Participants with glaucoma, both those with and without reduced central acuity, required a shorter viewing distance (i.e., a larger face) than did controls to recognize both the sex (by 2.59 m, F 1,30 ¼ 8.7, P < 0.006) and the facial expression (by 3.64 m, F 1,30 ¼ 14, P < 0.001). No significant difference was found between younger and older controls.CONCLUSIONS. Face perception is a skill that is reliant on central vision. Our behavioral results are consistent with the hypothesis of reduced central sensitivity in glaucoma. We suggest that the necessity to view larger faces in patients might result from a higher sensitivity to crowding that increases the difficulty to perceive the relevant features for recognition of both sex and facial expressions, akin to normal peripheral vision.

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Section: Discussionmentioning

confidence: 99%

Glaucoma Affects Viewing Distance for Recognition of Sex and Facial Expression

Schafer

Rouland

Peyrin

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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“…Inter-observer variability on central crowding has been reported previously in another ocular pathology: strabismic amblyopia. [36][37] Limitations: In contrast to the literature no crowding effect was observed in normally sighted controls. The experimental conditions: an exposure duration long enough to trigger a saccade and a large edge-to-edge spacing might be responsible for the lack of crowding effect and a performance at ceiling in this group.…”

Section: Discussionmentioning

confidence: 85%

Higher susceptibility to central crowding in glaucoma

Blanckaert

Rouland

Davost

et al. 2022

Clinical and Experimental Optometry

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Crowding limits many daily life activities, such as reading and the visual search for objects in cluttered environments. Excessive sensitivity to crowding, especially in central vision, may amplify the difficulties of patients with ocular pathologies. It is thus important to investigate what limits visual activities and how to improve it.Background: Numerous studies have reported reduced contrast sensitivity in central vision in patients with glaucoma. However, deficits have also been observed for letter recognition at high contrast, suggesting that contrast alone cannot completely account for impaired central perception.Method: Seventeen patients and fifteen age-matched controls were randomly presented with letters in central or parafoveal vision at 5° eccentricity for 200 ms. They were asked to decide whether the central T was upright or inverted. The T was either presented in isolation (uncrowded) or flanked by two Hs (crowded) at various spacings. Contrast was manipulated: 60% and 5%.Results: Compared to controls, patients exhibited a significant effect of crowding in central vision, with higher accuracy for the isolated T than for HTH only at low contrast. In parafoveal vision, an effect of crowding was also observed only in patients. The spacing to escape crowding varied as a function of contrast. Larger spacing was required at low contrast than at high contrast. Susceptibility to crowding was related to central visual field defect for central presentations and to contrast sensitivity for parafoveal presentations, only at low contrast. Controls were at ceiling level both for central and parafoveal presentations. Conclusion:Crowding limits visual perception, impeding reading and object recognition in cluttered environments. We demonstrate that visual field defect and lower contrast sensitivity in glaucoma can increase susceptibility to central and parafoveal crowding, the deleterious effect of which can be improved by manipulating contrast and spacing between elements.

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“…14 Vision charts in which a target is surrounded by flankers are recommended for children's vision screening programs to detect amblyopia, 25,26 as crowding is exaggerated if strabismus is present. [27][28][29][30][31] In currently available tests, targets are flanked by a box, [32][33][34] bars, 35 or other letters, 36 but these flanking features can have different effects on visual acuity in adults 4 and children. 37 Compared to effects of simple contours such as a box or bars, other letters placed around a target letter can lead to stronger interactions.…”

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confidence: 99%

Grouping Effects on Foveal Spatial Interactions in Children

Waugh

Formankiewicz

2020

Invest. Ophthalmol. Vis. Sci.

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Grouping of flankers from the target can modulate crowding in adults. Visual acuity in children is measured clinically using charts with targets and different flankers to enhance spatial interactions. We investigated grouping effects on interactions using visual acuity letters, flanked by contours and letters, in children. METHODS. Visual acuity for isolated and flanked letters was measured in 155 three-to 11-year old children and 32 adults. Flankers were one stroke width from the target and were a box or four bars and black or red letters. Magnitudes of interaction were flanked minus isolated logMAR acuities. Psychometric function slopes were also examined. RESULTS. Magnitudes of interaction by contours did not change significantly with age. They were 0.047 ± 0.014 logMAR more with bars than a box. Interaction from flanking letters reduced with age, adults being not different from 9-to 11-year-olds for black and red letter surrounds. It was weaker by 0.033 ± 0.013 logMAR when a black letter was surrounded by red rather than black letters. Psychometric function slopes for visual acuity were steepest for the youngest children (3-5 years). CONCLUSIONS. For contour and letter flankers, grouping effects on interaction magnitude are age independent. Grouping bars into a box forming a single object reduces magnitude of effect. Grouping letter flankers by color and ungrouping them from the target reduce interaction magnitude by ∼8%, suggesting that luminance-defined form dominates. Differently colored letter flankers of high-luminance contrast on acuity charts could draw attention to the target but retain significant interaction strength.

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Effect of stimulus configuration on crowding in strabismic amblyopia

Cited by 7 publications

References 73 publications

Glaucoma Affects Viewing Distance for Recognition of Sex and Facial Expression

Glaucoma Affects Viewing Distance for Recognition of Sex and Facial Expression

Higher susceptibility to central crowding in glaucoma

Grouping Effects on Foveal Spatial Interactions in Children

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