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Webber AL, Schmid KL, Baldwin AS, Hess RF. Suppression Rather Than Visual Acuity Loss Limits Stereoacuity in Amblyopia. Invest Ophthalmol Vis Sci 2021; 61:50. [PMID: 32579677 PMCID: PMC7419721 DOI: 10.1167/iovs.61.6.50] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the influence of interocular suppression and visual acuity loss on stereoacuity in observers with and without abnormal vision development from strabismus or amblyopia. To determine whether stereoacuity improves in amblyopic observers when suppression is neutralized. Methods Experiment 1: Visual acuity (VA), depth of suppression (contrast ratio [CR]), and stereoacuity (digital random-dot) were tested in adult amblyopic observers (n = 21; age 27 ± 11 years). Experiment 2: VA, stereoacuity, and CR were measured at baseline and through a series of monocular contrast attenuation and Bangerter filter conditions that degrade visual input in participants with normal binocular vision (n = 19; age 31 ± 13 years). Multiple regression models were used to determine relative contribution of VA and CR to stereoacuity in both groups. Experiment 3: stereoacuity was retested in a subsample of amblyopic observers (n = 7) after contrast reduction of the stimulus presented to dominant eye to neutralize suppression. Results In amblyopic observers, stereoacuity significantly correlated with CR (P < 0.001), but not with interocular VA difference (P = 0.863). In participants with normal vision development, stereoacuity, VA, and CR declined with introduction of monocular Bangerter filter (P < 0.001), and stereoacuity reduced with monocular attenuation of stimulus contrast (P < 0.001). Reduction in stereoacuity correlated with both VA decrement and degraded CR. Stereoacuity significantly improved in amblyopic observers when the contrast to the dominant eye was adjusted based on the contrast ratio. Conclusions Suppression rather than visual acuity loss limits stereoacuity in observers with abnormal vision development. Stereopsis can be improved when interocular sensory dominance is neutralized.
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Webber AL, Mandall TR, Molloy DT, Lister LJ, Birch EE. Worth 4 Dot App for Determining Size and Depth of Suppression. Transl Vis Sci Technol 2020; 9:9. [PMID: 32818097 PMCID: PMC7396169 DOI: 10.1167/tvst.9.4.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/13/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose To describe and evaluate an iOS application suppression test, Worth 4 Dot App (W4DApp), which was designed and developed to assess size and depth of suppression. Methods Characteristics of sensory fusion were evaluated in 25 participants (age 12–69 years) with normal (n = 6) and abnormal (n = 19) binocular vision. Suppression zone size and classification of fusion were determined by W4DApp and by flashlight Worth 4 Dot (W4D) responses from 33 cm to 6 m. Measures of suppression depth were compared between the W4DApp, the flashlight W4D with neutral density filter bar and the dichoptic letters contrast balance index test. Results There was high agreement in classification of fusion between the W4DApp method and that derived from flashlight W4D responses from 33 cm to 6 m (α = 0.817). There were no significant differences in success rates or in reliability between the W4DApp or the flashlight W4D methods for determining suppression zone size. W4DApp suppression zone size strongly correlated to that determined with the flashlight W4D (rho = 0.964, P < 0.001). W4DApp depth of suppression measures showed significantly higher success rates (χ2 = 5.128, P = 0.043) and reliability (intraclass correlation analysis = 0.901) but no significant correlation to the depth of suppression calculated by flashlight W4D and neutral density bar (rho = 0.301, P = 0.399) or contrast balance index (rho = −0.018, P = 0.958). Conclusions The W4DApp has potential clinical benefit in measuring suppression zone size; however, further modifications are required to improve validity of suppression depth measures. Translational Relevance W4DApp iOS application will be a convenient tool for clinical determination of suppression characteristics.
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Affiliation(s)
- Ann L Webber
- School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Thomas R Mandall
- School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Darcy T Molloy
- School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Lucas J Lister
- School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Eileen E Birch
- Retina Foundation of the Southwest, Dallas, TX, USA.,UT Southwestern Medical Center, Dallas, TX, USA
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Birch EE, Morale SE, Jost RM, De La Cruz A, Kelly KR, Wang YZ, Bex PJ. Assessing Suppression in Amblyopic Children With a Dichoptic Eye Chart. Invest Ophthalmol Vis Sci 2017; 57:5649-5654. [PMID: 27784068 PMCID: PMC5089215 DOI: 10.1167/iovs.16-19986] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Suppression has a key role in the etiology of amblyopia, and contrast-balanced binocular treatment can overcome suppression and improve visual acuity. Quantitative assessment of suppression could have a role in managing amblyopia. We describe a novel eye chart to assess suppression in children. Methods We enrolled 100 children (7–12 years; 63 amblyopic, 25 nonamblyopic with strabismus or anisometropia, 12 controls) in the primary cohort and 22 children (3–6 years; 13 amblyopic, 9 nonamblyopic) in a secondary cohort. Letters were presented on a dichoptic display (5 letters per line). Children wore polarized glasses so that each eye saw a different letter chart. At each position, the identity of the letter and its contrast on each eye's chart differed. Children read 8 lines of letters for each of 3 letter sizes. The contrast balance ratio was the ratio at which 50% of letters seen by the amblyopic eye were reported. Results Amblyopic children had significantly higher contrast balance ratios for all letter sizes compared to nonamblyopic children and controls, requiring 4.6 to 5.6 times more contrast in the amblyopic eye compared to the fellow eye (P < 0.0001). Amblyopic eye visual acuity was correlated with contrast balance ratio (r ranged from 0.49–0.57 for the 3 letter sizes). Change in visual acuity with amblyopia treatment was correlated with change in contrast balance ratio (r ranged from 0.43–0.62 for the 3 letter sizes). Conclusions Severity of suppression can be monitored as part of a routine clinical exam in the management of amblyopia in children.
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Affiliation(s)
- Eileen E Birch
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Sarah E Morale
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Reed M Jost
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Angie De La Cruz
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Krista R Kelly
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Yi-Zhong Wang
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Peter J Bex
- Department of Psychology, Northeastern University, Boston, Massachusetts, United States
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Guo CX, Babu RJ, Black JM, Bobier WR, Lam CSY, Dai S, Gao TY, Hess RF, Jenkins M, Jiang Y, Kowal L, Parag V, South J, Staffieri SE, Walker N, Wadham A, Thompson B. Binocular treatment of amblyopia using videogames (BRAVO): study protocol for a randomised controlled trial. Trials 2016; 17:504. [PMID: 27756405 PMCID: PMC5069878 DOI: 10.1186/s13063-016-1635-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 09/30/2016] [Indexed: 12/02/2022] Open
Abstract
Background Amblyopia is a common neurodevelopmental disorder of vision that is characterised by visual impairment in one eye and compromised binocular visual function. Existing evidence-based treatments for children include patching the nonamblyopic eye to encourage use of the amblyopic eye. Currently there are no widely accepted treatments available for adults with amblyopia. The aim of this trial is to assess the efficacy of a new binocular, videogame-based treatment for amblyopia in older children and adults. We hypothesise that binocular treatment will significantly improve amblyopic eye visual acuity relative to placebo treatment. Methods/design The BRAVO study is a double-blind, randomised, placebo-controlled multicentre trial to assess the effectiveness of a novel videogame-based binocular treatment for amblyopia. One hundred and eight participants aged 7 years or older with anisometropic and/or strabismic amblyopia (defined as ≥0.2 LogMAR interocular visual acuity difference, ≥0.3 LogMAR amblyopic eye visual acuity and no ocular disease) will be recruited via ophthalmologists, optometrists, clinical record searches and public advertisements at five sites in New Zealand, Canada, Hong Kong and Australia. Eligible participants will be randomised by computer in a 1:1 ratio, with stratification by age group: 7–12, 13–17 and 18 years and older. Participants will be randomised to receive 6 weeks of active or placebo home-based binocular treatment. Treatment will be in the form of a modified interactive falling-blocks game, implemented on a 5th generation iPod touch device viewed through red/green anaglyphic glasses. Participants and those assessing outcomes will be blinded to group assignment. The primary outcome is the change in best-corrected distance visual acuity in the amblyopic eye from baseline to 6 weeks post randomisation. Secondary outcomes include distance and near visual acuity, stereopsis, interocular suppression, angle of strabismus (where applicable) measured at baseline, 3, 6, 12 and 24 weeks post randomisation. Treatment compliance and acceptability will also be assessed along with quality of life for adult participants. Discussion The BRAVO study is the first randomised controlled trial of a home-based videogame treatment for older children and adults with amblyopia. The results will indicate whether a binocular approach to amblyopia treatment conducted at home is effective for patients aged 7 years or older. Trial registration This trial was registered in Australia and New Zealand Clinical Trials Registry (ACTRN12613001004752) on 10 September 2013.
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Affiliation(s)
- Cindy X Guo
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Raiju J Babu
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Joanna M Black
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - William R Bobier
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Carly S Y Lam
- School of Optometry, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hong Kong, SAR, China
| | - Shuan Dai
- Department of Ophthalmology, Starship Children's Hospital, Auckland, New Zealand
| | - Tina Y Gao
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Robert F Hess
- Department of Ophthalmology, McGill Vision Research, McGill University, Montreal, QC, Canada
| | - Michelle Jenkins
- National Institute for Health Innovation, School of Population Health, The University of Auckland, Auckland, New Zealand
| | - Yannan Jiang
- National Institute for Health Innovation, School of Population Health, The University of Auckland, Auckland, New Zealand
| | - Lionel Kowal
- Department of Surgery, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital; Ophthalmology, University of Melbourne, Melbourne, VIC, Australia
| | - Varsha Parag
- National Institute for Health Innovation, School of Population Health, The University of Auckland, Auckland, New Zealand
| | - Jayshree South
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Sandra Elfride Staffieri
- Department of Surgery, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital; Ophthalmology, University of Melbourne, Melbourne, VIC, Australia
| | - Natalie Walker
- National Institute for Health Innovation, School of Population Health, The University of Auckland, Auckland, New Zealand
| | - Angela Wadham
- National Institute for Health Innovation, School of Population Health, The University of Auckland, Auckland, New Zealand
| | - Benjamin Thompson
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand. .,School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada.
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Vedamurthy I, Nahum M, Bavelier D, Levi DM. Mechanisms of recovery of visual function in adult amblyopia through a tailored action video game. Sci Rep 2015; 5:8482. [PMID: 25719537 PMCID: PMC4894407 DOI: 10.1038/srep08482] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 12/24/2014] [Indexed: 11/09/2022] Open
Abstract
Amblyopia is a deficit in vision that arises from abnormal visual experience early in life. It was long thought to develop into a permanent deficit, unless properly treated before the end of the sensitive period for visual recovery. However, a number of studies now suggest that adults with long-standing amblyopia may at least partially recover visual acuity and stereopsis following perceptual training. Eliminating or reducing interocular suppression has been hypothesized to be at the root of these changes. Here we show that playing a novel dichoptic video game indeed results in reduced suppression, improved visual acuity and, in some cases, improved stereopsis. Our relatively large cohort of adults with amblyopia, allowed us, for the first time, to assess the link between visual function recovery and reduction in suppression. Surprisingly, no significant correlation was found between decreased suppression and improved visual function. This finding challenges the prevailing view and suggests that while dichoptic training improves visual acuity and stereopsis in adult amblyopia, reduced suppression is unlikely to be at the root of visual recovery. These results are discussed in the context of their implication on recovery of amblyopia in adults.
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Affiliation(s)
- Indu Vedamurthy
- Department of Brain &Cognitive Sciences, University of Rochester. Rochester, New York 14627-0268, U.S.A
| | - Mor Nahum
- School of Optometry, Graduate Group in Vision Science and Helen Wills Neuroscience Institute, University of California, Berkeley. Berkeley, California, 94720-2020
| | - Daphne Bavelier
- 1] Department of Brain &Cognitive Sciences, University of Rochester. Rochester, New York 14627-0268, U.S.A [2] Faculty of Psychology and Education Sciences, University of Geneva, Switzerland
| | - Dennis M Levi
- School of Optometry, Graduate Group in Vision Science and Helen Wills Neuroscience Institute, University of California, Berkeley. Berkeley, California, 94720-2020
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Hamm LM, Black J, Dai S, Thompson B. Global processing in amblyopia: a review. Front Psychol 2014; 5:583. [PMID: 24987383 PMCID: PMC4060804 DOI: 10.3389/fpsyg.2014.00583] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/25/2014] [Indexed: 01/13/2023] Open
Abstract
Amblyopia is a neurodevelopmental disorder of the visual system that is associated with disrupted binocular vision during early childhood. There is evidence that the effects of amblyopia extend beyond the primary visual cortex to regions of the dorsal and ventral extra-striate visual cortex involved in visual integration. Here, we review the current literature on global processing deficits in observers with either strabismic, anisometropic, or deprivation amblyopia. A range of global processing tasks have been used to investigate the extent of the cortical deficit in amblyopia including: global motion perception, global form perception, face perception, and biological motion. These tasks appear to be differentially affected by amblyopia. In general, observers with unilateral amblyopia appear to show deficits for local spatial processing and global tasks that require the segregation of signal from noise. In bilateral cases, the global processing deficits are exaggerated, and appear to extend to specialized perceptual systems such as those involved in face processing.
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Affiliation(s)
- Lisa M Hamm
- Department of Optometry and Vision Science, University of Auckland Auckland, New Zealand
| | - Joanna Black
- Department of Optometry and Vision Science, University of Auckland Auckland, New Zealand
| | - Shuan Dai
- Department of Ophthalmology, Starship Children's Hospital Auckland, New Zealand ; Department of Ophthalmology, University of Auckland Auckland, New Zealand
| | - Benjamin Thompson
- Department of Optometry and Vision Science, University of Auckland Auckland, New Zealand ; Department of Optometry and Vision Science, University of Waterloo Waterloo, Canada
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