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Article ; Online: Mechanisms of recovery of visual function in adult amblyopia through a tailored action video game.

Vedamurthy, Indu / Nahum, Mor / Bavelier, Daphne / Levi, Dennis M

2015 Volume 5, Page(s) 8482

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 ... ...

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.
MeSH term(s)	Adult ; Amblyopia/physiopathology ; Amblyopia/therapy ; Depth Perception ; Humans ; Middle Aged ; Perceptual Disorders/physiopathology ; Perceptual Disorders/therapy ; Photic Stimulation ; Recovery of Function ; Video Games ; Vision, Binocular ; Visual Acuity ; Young Adult
Language	English
Publishing date	2015-02-26
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/srep08482
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Article ; Online: An action video game for the treatment of amblyopia in children: A feasibility study.

Gambacorta, Christina / Nahum, Mor / Vedamurthy, Indu / Bayliss, Jessica / Jordan, Josh / Bavelier, Daphne / Levi, Dennis M

Vision research

2018 Volume 148, Page(s) 1–14

Abstract: The gold-standard treatment for childhood amblyopia remains patching or penalizing the fellow eye, resulting in an average of about a one line (0.1 logMAR) improvement in visual acuity following ≈120 h of patching in children 3-8 years old. However, ... ...

Abstract	The gold-standard treatment for childhood amblyopia remains patching or penalizing the fellow eye, resulting in an average of about a one line (0.1 logMAR) improvement in visual acuity following ≈120 h of patching in children 3-8 years old. However, compliance with patching and other treatment options is often poor. In contrast, fast-paced action video games can be highly engaging, and have been shown to yield broad-based improvements in vision and attention in adult amblyopia. Here, we pilot-tested a custom-made action video game to treat children with amblyopia. Twenty-one (n = 21) children (mean age 9.95 ± 3.14 [se]) with unilateral amblyopia (n = 12 anisometropic and n = 9 strabismic) completed 20 h of game play either monocularly, with the fellow eye patched (n = 11), or dichoptically, with reduced contrast to the fellow eye (n = 10). Participants were assessed for visual acuity (VA), stereo acuity and reading speed at baseline, and following 10 and 20 h of play. Additional exploratory analyses examined improvements after 6-10 weeks of completion of training (follow-up). Following 20 h of training, VA improved, on average, by 0.14 logMAR (≈38%) for the dichoptic group and by 0.06 logMAR (≈15%) for the monocular group. Similarly, stereoacuity improved by 0.07 log arcsec (≈17%) following dichoptic training, and by 0.06 log arcsec (≈15%) following monocular training. Across both treatment groups, 7 of the 12 individuals with anisometropic amblyopia showed improvement in stereoacuity, whereas only 1 of the 9 strabismic individuals improved. Most improvements were largely retained at follow-up. Our feasibility study therefore suggests that the action video game approach may be used as an effective adjunct treatment for amblyopia in children, achieving results similar to those of the gold-standard treatment in shorter duration.
MeSH term(s)	Adolescent ; Amblyopia/therapy ; Child ; Eyeglasses ; Feasibility Studies ; Female ; Humans ; Male ; Sensory Deprivation ; Time Factors ; Video Games ; Visual Acuity/physiology
Language	English
Publishing date	2018-05-12
Publishing country	England
Document type	Comparative Study ; Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	200427-6
ISSN	1878-5646 ; 0042-6989
ISSN (online)	1878-5646
ISSN	0042-6989
DOI	10.1016/j.visres.2018.04.005
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Article ; Online: Recovering stereo vision by squashing virtual bugs in a virtual reality environment.

Vedamurthy, Indu / Knill, David C / Huang, Samuel J / Yung, Amanda / Ding, Jian / Kwon, Oh-Sang / Bavelier, Daphne / Levi, Dennis M

Philosophical transactions of the Royal Society of London. Series B, Biological sciences

2016 Volume 371, Issue 1697

Abstract: Stereopsis is the rich impression of three-dimensionality, based on binocular disparity-the differences between the two retinal images of the same world. However, a substantial proportion of the population is stereo-deficient, and relies mostly on ... ...

Abstract	Stereopsis is the rich impression of three-dimensionality, based on binocular disparity-the differences between the two retinal images of the same world. However, a substantial proportion of the population is stereo-deficient, and relies mostly on monocular cues to judge the relative depth or distance of objects in the environment. Here we trained adults who were stereo blind or stereo-deficient owing to strabismus and/or amblyopia in a natural visuomotor task-a 'bug squashing' game-in a virtual reality environment. The subjects' task was to squash a virtual dichoptic bug on a slanted surface, by hitting it with a physical cylinder they held in their hand. The perceived surface slant was determined by monocular texture and stereoscopic cues, with these cues being either consistent or in conflict, allowing us to track the relative weighting of monocular versus stereoscopic cues as training in the task progressed. Following training most participants showed greater reliance on stereoscopic cues, reduced suppression and improved stereoacuity. Importantly, the training-induced changes in relative stereo weights were significant predictors of the improvements in stereoacuity. We conclude that some adults deprived of normal binocular vision and insensitive to the disparity information can, with appropriate experience, recover access to more reliable stereoscopic information.This article is part of the themed issue 'Vision in our three-dimensional world'.
MeSH term(s)	Adult ; Amblyopia/therapy ; Depth Perception/physiology ; Humans ; Middle Aged ; Perceptual Disorders/therapy ; Strabismus/therapy ; Treatment Outcome ; Virtual Reality Exposure Therapy/instrumentation ; Virtual Reality Exposure Therapy/methods ; Virtual Reality Exposure Therapy/standards
Language	English
Publishing date	2016-06-03
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	208382-6
ISSN	1471-2970 ; 0080-4622 ; 0264-3839 ; 0962-8436
ISSN (online)	1471-2970
ISSN	0080-4622 ; 0264-3839 ; 0962-8436
DOI	10.1098/rstb.2015.0264
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Article ; Online: Short-term adaptive modification of dynamic ocular accommodation.

Bharadwaj, Shrikant R / Vedamurthy, Indu / Schor, Clifton M

Investigative ophthalmology & visual science

2009 Volume 50, Issue 7, Page(s) 3520–3528

Abstract: Purpose: Indirect observations suggest that the neural control of accommodation may undergo adaptive recalibration in response to age-related biomechanical changes in the accommodative system. However, there has been no direct demonstration of such an ... ...

Abstract	Purpose: Indirect observations suggest that the neural control of accommodation may undergo adaptive recalibration in response to age-related biomechanical changes in the accommodative system. However, there has been no direct demonstration of such an adaptive capability. This investigation was conducted to demonstrate short-term adaptation of accommodative step response dynamics to optically induced changes in neuromuscular demands. Methods: Repetitive changes in accommodative effort were induced in 15 subjects (18-34 years) with a double-step adaptation paradigm wherein an initial 2-D step change in blur was followed 350 ms later by either a 2-D step increase in blur (increasing-step paradigm) or a 1.75-D step decrease in blur (decreasing-step paradigm). Peak velocity, peak acceleration, and latency of 2-D single-step test responses were assessed before and after 1.5 hours of training with these paradigms. Results: Peak velocity and peak acceleration of 2-D step responses increased after adaptation to the increasing-step paradigm (9/12 subjects), and they decreased after adaptation to the decreasing-step paradigm (4/9 subjects). Adaptive changes in peak velocity and peak acceleration generalized to responses that were smaller (1 D) and larger (3 D) than the 2-D adaptation stimulus. The magnitude of adaptation correlated poorly with the subject's age, but it was significantly negatively correlated with the preadaptation dynamics. Response latency decreased after adaptation, irrespective of the direction of adaptation. Conclusions: Short-term adaptive changes in accommodative step response dynamics could be induced, at least in some of our subjects between 18 and 34 years, with a directional bias toward increasing rather than decreasing the dynamics.
MeSH term(s)	Accommodation, Ocular/physiology ; Adaptation, Ocular/physiology ; Adolescent ; Adult ; Humans ; Mydriatics/pharmacology ; Phenylephrine/pharmacology ; Photic Stimulation ; Pupil/drug effects ; Young Adult
Chemical Substances	Mydriatics ; Phenylephrine (1WS297W6MV)
Language	English
Publishing date	2009-02-28
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	391794-0
ISSN	1552-5783 ; 0146-0404
ISSN (online)	1552-5783
ISSN	0146-0404
DOI	10.1167/iovs.08-2577
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Article: Cross-coupling between accommodation and convergence is optimized for a broad range of directions and distances of gaze.

Nguyen, Dorothy / Vedamurthy, Indu / Schor, Clifton

Vision research

2008 Volume 48, Issue 7, Page(s) 893–903

Abstract: Accommodation and convergence systems are cross-coupled so that stimulation of one system produces responses by both systems. Ideally, the cross-coupled responses of accommodation and convergence match their respective stimuli. When expressed in diopters ...

Abstract	Accommodation and convergence systems are cross-coupled so that stimulation of one system produces responses by both systems. Ideally, the cross-coupled responses of accommodation and convergence match their respective stimuli. When expressed in diopters and meter angles, respectively, stimuli for accommodation and convergence are equal in the mid-sagittal plane when viewed with symmetrical convergence, where historically, the gains of the cross coupling (AC/A and CA/C ratios) have been quantified. However, targets at non-zero azimuth angles, when viewed with asymmetric convergence, present unequal stimuli for accommodation and convergence. Are the cross-links between the two systems calibrated to compensate for stimulus mismatches that increase with gaze-azimuth? We measured the response AC/A and stimulus CA/C ratios at zero azimuth, 17.5 and 30 deg of rightward gaze eccentricities with a Badal Optometer and Wheatstone-mirror haploscope. AC/A ratios were measured under open-loop convergence conditions along the iso-accommodation circle (locus of points that stimulate approximately equal amounts of accommodation to the two eyes at all azimuth angles). CA/C ratios were measured under open-loop accommodation conditions along the iso-vergence circle (locus of points that stimulate constant convergence at all azimuth angles). Our results show that the gain of accommodative-convergence (AC/A ratio) decreased and the bias of convergence-accommodation increased at the 30 deg gaze eccentricity. These changes are in directions that compensate for stimulus mismatches caused by spatial-viewing geometry during asymmetric convergence.
MeSH term(s)	Accommodation, Ocular/physiology ; Adult ; Convergence, Ocular/physiology ; Distance Perception/physiology ; Feedback/physiology ; Humans ; Photic Stimulation/methods ; Vision Disparity/physiology
Language	English
Publishing date	2008-02-20
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	200427-6
ISSN	1878-5646 ; 0042-6989
ISSN (online)	1878-5646
ISSN	0042-6989
DOI	10.1016/j.visres.2008.01.002
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Article ; Online: A dichoptic custom-made action video game as a treatment for adult amblyopia.

Vedamurthy, Indu / Nahum, Mor / Huang, Samuel J / Zheng, Frank / Bayliss, Jessica / Bavelier, Daphne / Levi, Dennis M

Vision research

2015 Volume 114, Page(s) 173–187

Abstract: Previous studies have employed different experimental approaches to enhance visual function in adults with amblyopia including perceptual learning, videogame play, and dichoptic training. Here, we evaluated the efficacy of a novel dichoptic action ... ...

Abstract	Previous studies have employed different experimental approaches to enhance visual function in adults with amblyopia including perceptual learning, videogame play, and dichoptic training. Here, we evaluated the efficacy of a novel dichoptic action videogame combining all three approaches. This experimental intervention was compared to a conventional, yet unstudied method of supervised occlusion while watching movies. Adults with unilateral amblyopia were assigned to either play the dichoptic action game (n=23; 'game' group), or to watch movies monocularly while the fellow eye was patched (n=15; 'movies' group) for a total of 40hours. Following training, visual acuity (VA) improved on average by ≈0.14logMAR (≈28%) in the game group, with improvements noted in both anisometropic and strabismic patients. This improvement is similar to that obtained following perceptual learning, video game play or dichoptic training. Surprisingly, patients with anisometropic amblyopia in the movies group showed similar improvement, revealing a greater impact of supervised occlusion in adults than typically thought. Stereoacuity, reading speed, and contrast sensitivity improved more for game group participants compared with movies group participants. Most improvements were largely retained following a 2-month no-contact period. This novel video game, which combines action gaming, perceptual learning and dichoptic presentation, results in VA improvements equivalent to those previously documented with each of these techniques alone. Our game intervention led to greater improvement than control training in a variety of visual functions, thus suggesting that this approach has promise for the treatment of adult amblyopia.
MeSH term(s)	Adult ; Aged ; Amblyopia/physiopathology ; Amblyopia/therapy ; Analysis of Variance ; Contrast Sensitivity/physiology ; Depth Perception/physiology ; Female ; Humans ; Male ; Middle Aged ; Photic Stimulation/methods ; Reading ; Time Factors ; Video Games ; Vision, Binocular/physiology ; Visual Acuity/physiology ; Young Adult
Language	English
Publishing date	2015-09
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	200427-6
ISSN	1878-5646 ; 0042-6989
ISSN (online)	1878-5646
ISSN	0042-6989
DOI	10.1016/j.visres.2015.04.008
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Article: A psychophysical study of human binocular interactions in normal and amblyopic visual systems.

Vedamurthy, Indu / Suttle, Catherine M / Alexander, Jack / Asper, Lisa J

Vision research

2008 Volume 48, Issue 14, Page(s) 1522–1531

Abstract: During infancy and childhood, spatial contrast sensitivity and alignment sensitivity undergo maturation, and during this period the visual system has considerable plasticity. The purpose of this study was to compare the nature of interocular interactions ...

Abstract	During infancy and childhood, spatial contrast sensitivity and alignment sensitivity undergo maturation, and during this period the visual system has considerable plasticity. The purpose of this study was to compare the nature of interocular interactions of these spatial functions in normally sighted children and adults, and to study the extent to which interocular interactions are impaired in anisometropic amblyopia. Spatial functions were measured under three viewing conditions: monocular (fellow eye occluded), dichoptic (uniform stimulus presented to the fellow eye but with a peripheral fusion lock), and binocular. Measurements were made in each eye during monocular and dichoptic viewing. In the contrast sensitivity task, Gabor stimuli were presented in one of two temporal intervals. For the alignment task, a three-element Gabor stimulus was used. The task of the subject was to indicate the direction of displacement of the middle patch with respect to the outer patches. The findings indicate that in children, binocular contrast sensitivity was better than monocular (binocular summation) but so too was dichoptic sensitivity (dichoptic summation). The magnitude of binocular/dichoptic summation was significantly greater in children than in normally sighted adults for contrast sensitivity, but not for alignment sensitivity. In anisometropic amblyopes, however, we find that for the group as a whole the amblyopic eye does not benefit when the fellow eye views a dichoptic stimulus, compared to dark occlusion of that eye. In addition, we found considerable inter-individual variation within the amblyopic group. Implications of these findings for techniques used in vision therapy are discussed.
MeSH term(s)	Adolescent ; Adult ; Amblyopia/physiopathology ; Amblyopia/psychology ; Child ; Contrast Sensitivity ; Dominance, Ocular ; Female ; Humans ; Male ; Photic Stimulation/methods ; Psychophysics ; Vision, Binocular ; Visual Acuity
Language	English
Publishing date	2008-06
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	200427-6
ISSN	1878-5646 ; 0042-6989
ISSN (online)	1878-5646
ISSN	0042-6989
DOI	10.1016/j.visres.2008.04.004
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Article: Effects of accommodation training on accommodation and depth of focus in an eye implanted with a crystalens intraocular lens.

Tahir, Humza J / Tong, Jian L / Geissler, Sydney / Vedamurthy, Indu / Schor, Clifton M

Journal of refractive surgery (Thorofare, N.J. : 1995)

2010 Volume 26, Issue 10, Page(s) 772–779

Abstract: Purpose: To investigate objective measures of the effects of accommodative training of a pseudophakic eye implanted with a Crystalens AT-52SE (eyeonics Inc) intraocular lens (IOL) on reading performance, accommodation, and depth of focus.: Methods: ... ...

Abstract	Purpose: To investigate objective measures of the effects of accommodative training of a pseudophakic eye implanted with a Crystalens AT-52SE (eyeonics Inc) intraocular lens (IOL) on reading performance, accommodation, and depth of focus. Methods: Objective dynamic measures of accommodation, pupil size, and depth of focus were quantified from wavefront measures before and after 1 week of accommodative training that began 29 months after implantation of an accommodating IOL in one patient. Depth of focus was estimated from 50% cut-off of peak performance levels for defocus curves that were computed from the image quality metric VSOTF based on ocular wavefront aberrations. Results: The patient reported improved near vision reading performance after completing the training procedure. After training, there was a shift in conjugate focus in the hyperopic direction, yet the depth of focus increased significantly for near objects. Simulated retinal images and the calculated modulation transfer function of the eye both demonstrated improved quality for near vision after training. Conclusions: The subjective report of improved near vision after training was correlated with improvement of objective measures. Depth of focus increased for near objects with attempts to accommodate after training. This change was linked to increases in aberrations and pupil size and occurred despite the conjugate focus shifting in the hyperopic direction. These results demonstrate that accommodative training may be useful in improving near vision in patients with accommodating IOLs.
MeSH term(s)	Accommodation, Ocular/physiology ; Adaptation, Ocular/physiology ; Depth Perception/physiology ; Exercise Therapy ; Female ; Humans ; Lens Implantation, Intraocular ; Lenses, Intraocular ; Middle Aged ; Prosthesis Design ; Reading ; Refraction, Ocular/physiology ; Retina/physiology ; Visual Acuity/physiology
Language	English
Publishing date	2010-09-30
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ISSN	1081-597X
ISSN	1081-597X
DOI	10.3928/1081597X-20100921-02
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Article: Interocular interactions during acuity measurement in children and adults, and in adults with amblyopia.

Vedamurthy, Indu / Suttle, Catherine M / Alexander, Jack / Asper, Lisa J

Vision research

2007 Volume 47, Issue 2, Page(s) 179–188

Abstract: The binocular interactions that occur during dichoptic and binocular viewing were investigated using a letter acuity task in normally sighted children (age range 6-14 years) and adults, and in adults with anisometropic amblyopia. Our aims were to ... ...

Abstract	The binocular interactions that occur during dichoptic and binocular viewing were investigated using a letter acuity task in normally sighted children (age range 6-14 years) and adults, and in adults with anisometropic amblyopia. Our aims were to investigate the nature of binocular interactions that occur in each group, and the extent to which the characteristics of binocular interactions differ across the groups. The non-tested eye was occluded during monocular (baseline) viewing, and was allowed to view a uniform stimulus with fusion lock in dichoptic viewing. In adults and children with normal vision, acuity under dichoptic viewing was unchanged relative to monocular baseline in the dominant eyes, while acuity of the non-dominant eye improved under dichoptic viewing relative to baseline. The magnitude of dichoptic change in the non-dominant eyes was similar in the two normally sighted groups, but the dichoptic advantage was found to decrease with increasing age within the children tested. Binocular acuity was better than monocular acuity in normal subjects, and a decrease in binocular summation with age was noted within the age range of the children tested. In contrast, the amblyopic observers showed no change in acuity with viewing conditions. The results demonstrate development of interocular interactions during childhood, and wide inter-individual variation in pattern of interocular interactions among anisometropic amblyopic adults.
MeSH term(s)	Adolescent ; Adult ; Aging/physiology ; Amblyopia/physiopathology ; Child ; Female ; Humans ; Male ; Vision Disparity ; Vision Tests ; Vision, Binocular/physiology ; Vision, Monocular ; Visual Acuity/physiology
Language	English
Publishing date	2007-01
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	200427-6
ISSN	1878-5646 ; 0042-6989
ISSN (online)	1878-5646
ISSN	0042-6989
DOI	10.1016/j.visres.2006.08.017
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Article ; Online: The influence of first near-spectacle reading correction on accommodation and its interaction with convergence.

Vedamurthy, Indu / Harrison, Wendy W / Liu, Yue / Cox, Ian / Schor, Clifton M

Investigative ophthalmology & visual science

2009 Volume 50, Issue 9, Page(s) 4215–4222

Abstract: Purpose: Accommodation and convergence can adapt to blur and disparity stimuli and to age-related changes in accommodative amplitude. Does this ability decline with age? The authors investigated short-term adaptation to first near-spectacle reading ... ...

Abstract	Purpose: Accommodation and convergence can adapt to blur and disparity stimuli and to age-related changes in accommodative amplitude. Does this ability decline with age? The authors investigated short-term adaptation to first near-spectacle reading correction on the accommodative-stimulus response (ASR) function, accommodative amplitude (AA), AC/A, and CA/C ratios in a pre-presbyopic and an incipient presbyopic population and determined whether changes in these functions recovered after discontinuation of the use of near spectacles. Methods: Thirty subjects with normal vision participated; their ages ranged from 21 to 30 years (n = 15) and 38 to 44 years (n = 15). Oculomotor functions were measured before and after single-vision reading spectacles were worn for near tasks over a 2-month period and then 2 months after the use of near spectacles was discontinued. Results: The slope of the ASR function and the AC/A and CA/C ratios did not change significantly after near spectacles were worn. There was a hyperopic shift of the ASR function that significantly reduced the near point of accommodation (NPA) and lowered the far-point refraction. These changes were age invariant and did not recover after 2 months of discontinuation of near spectacle wear. Conclusions: These results imply that the NPA may be enhanced normally by tonic bias of accommodation that elevates the entire ASR function and produces myopic refraction bias. When this bias relaxes after reading spectacles are worn, there is a hyperopic shift of the refractive state and a reduction of the NPA, specified from optical infinity.
MeSH term(s)	Accommodation, Ocular/physiology ; Adaptation, Ocular/physiology ; Adult ; Convergence, Ocular/physiology ; Eyeglasses ; Humans ; Presbyopia/physiopathology ; Presbyopia/therapy ; Reading ; Refraction, Ocular/physiology ; Visual Acuity/physiology ; Young Adult
Language	English
Publishing date	2009-03-05
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	391794-0
ISSN	1552-5783 ; 0146-0404
ISSN (online)	1552-5783
ISSN	0146-0404
DOI	10.1167/iovs.08-3021
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