Ocular alignment is repeated before each measurement is started. The result obtained from each measurement is the threshold number of signal dots out of dots total required to correctly judge the direction when both eyes see the same stimuli.
The program also reports the range of responses as a standard error of the measurement. For the next measurement, the contrast staircase, the five results from the binocular staircases are averaged and the resulting threshold defines the number of signal dots presented to the amblyopic eye.
The remaining noise dots are presented to the non-amblyopic eye at varying contrasts to assess suppression. For this measurement the amblyopic eye always sees high contrast dots whereas the contrast of the noise dots shown to the non-amblyopic eye is varied using a staircase procedure.
At the start of the staircase a fixed number of signal dots obtained from step 1. Correct identification of the signal dot direction results in an increase in the contrast of the noise dots shown to the fellow eye according to the 3-down 1-up staircase algorithm.
This indicates that the signal and noise dots are being combined between the two eyes to produce the same level of task performance that was observed under binocular viewing conditions step 1. Increasing the contrast of the noise dots shown to the fellow eye above this point would result in suppression of the signal dots shown to the amblyopic eye and impairment in task performance.
Five measurements are made of the contrast imbalance and an average result is calculated. The result informs the examiner about the level of contrast imbalance that is necessary to overcome suppression and allow the amblyopic eye and fellow eye to see the dots simultaneously. The contrast imbalance found in step 1. The training involves integrating the use of dichoptic images with the contrast imbalance into a video game format "tetris".
The video game can be implemented on either the virtual reality goggles or on an ipod touch device. The video game tetris involves a series of falling blocks which are fitted together to form complete lines. The amblyopic eye sees full contrast blocks, and the fellow eye sees reduced contrast images.
Information presented to each eye must be perceived simultaneously for successful play. Over time as the training regime continues the contrast imbalance is reduced by increasing the contrast to the fellow eye, making it more difficult for the visual system to overcome the suppression caused by more similar dichoptic images.
Training duration should be hr a day and should be continued until no further improvement in contrast imbalance increase in contrast presented to the fellow eye is observed. During the training regime, checks of monocular and binocular function should be made regularly determined by age of patient and underlying condition.
Tests of monocular visual acuity, stereopsis and standard tests of suppression are particularly important for reporting progress. The level of suppression found in the described method is dependent on the underlying cause of the amblyopia, previous treatment, use of refractive correction and visual acuity.
Because each patient has a very unique history, it is difficult to define 'normal' values of suppression or make comparisons between people.
Generally we expect those with worse visual acuity to have a deeper level of suppression 9. During training, as we reduce the contrast imbalance between the eyes, the depth of suppression typically reduces and this improves a range of binocular and monocular functions.
This change in suppression has been demonstrated in several patient populations see Figures 3 and 4 in reference 12 , Table 3 and Figure 9 in reference 15 and Figure 2 in reference It is important to note that detailed measurements of suppression using this technique have the potential to enhance our understanding of the amblyopia syndrome. Figure 1. The equipment used for measuring suppression which includes 1 laptop 2 goggles 3 signal splitter.
Figure 3. An overview of the random dot kinetogram stimuli Step 1. The top panel demonstrates the alignment phase where a half cross is displayed to each eye monocularly as a cue for binocular alignment. The middle panel demonstrates the signal to noise paradigm where signal dots are presented to the amblyopic eye only and the noise dots are presented to the fellow eye, under binocular conditions the signal and noise are combined to give a motion coherence threshold which is then utilized in the contrast varying stage of the measurement.
The bottom panel demonstrates the contrast threshold, this procedure uses the motion coherence threshold at a fixed level of signal to noise, and displays varying contrast levels between the two eyes. The point at which the two eyes see a balanced binocular input is the contrast threshold or "balance point".
Figure 4. Step 1. Figure 6. Example of clinical and psychophysical data obtained from one adult participant with strabismic amblyopia who completed the training procedure steps 2. Song, S. A double dissociation of the acuity and crowding limits to letter identification and the promise of improved visual screening.
Prentice award lecture removing the brakes on plasticity in the amblyopic brain. Polat, U. Restoration of underdeveloped cortical functions: evidence from treatment of adult amblyopia. Google Scholar. Making perceptual learning practical to improve visual functions. Characterizing the mechanisms of improvement for position discrimination in adult amblyopia.
Extended perceptual learning results in substantial recovery of positional acuity and visual acuity in juvenile amblyopia. Zhang, J. Perceptual learning improves adult amblyopic vision through rule-based cognitive compensation.
Stereopsis and amblyopia: A mini-review. Bavelier, D. Removing brakes on adult brain plasticity: from molecular to behavioral interventions. Epic Games.
Unreal tournament, Green, C. Action video game modifies visual selective attention. Enhancing the contrast sensitivity function through action video game training.
Bayliss, J. Recovery of stereopsis through perceptual learning in human adults with abnormal binocular vision. USA , E— Levitt, H. Transformed up-down methods in psychoacoustics. Bouma, H. Interaction effects in parafoveal letter recognition. Crowding—an essential bottleneck for object recognition: a mini-review. Download references.
We thank Jessica Bayliss for her role in game development. You can also search for this author in PubMed Google Scholar. These authors contributed to the study design and conceptualization: D. These authors contributed to game development: I.
These authors contributed to piloting and fine-tuning, running the study and data analysis: I. All authors contributed to writing. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. Reprints and Permissions. Vedamurthy, I.
Mechanisms of recovery of visual function in adult amblyopia through a tailored action video game. Sci Rep 5, Download citation. Received : 31 July Accepted : 24 December Published : 26 February Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative.
Scientific Reports Journal of Cognitive Enhancement Graefe's Archive for Clinical and Experimental Ophthalmology By submitting a comment you agree to abide by our Terms and Community Guidelines.
If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Advanced search. Skip to main content Thank you for visiting nature. Download PDF. Subjects Neuroscience Pattern vision. Abstract Amblyopia is a deficit in vision that arises from abnormal visual experience early in life. Introduction Amblyopia is a deficit in vision that arises from abnormal visual experience early in life.
Results Interocular Ratio as an index for suppression At the beginning of each session, subjects carefully aligned the stereoscope and reduced the perceptual strength of the strong eye's image by adjusting the alpha value, see Methods for details relative to the amblyopic eye's image to perceptually equalize the input to the two eyes.
Table 1 Pre-training correlations Full size table. Figure 1. Pre-training baseline correlations with interocular suppression. Full size image. Figure 2. Video game training induced reduction in interocular suppression as measured by IOR.
Figure 3. Pre-training correlations with AE resolution. Figure 4. Discussion Playing a highly engaging, action-packed dichoptic first-person shooter video game, customized to incorporate a perceptual learning task and perceptually equated stimuli to the two eyes, results in reduced suppression, increased Gabor resolution, improved visual acuity and, in some cases, improved stereopsis in adults with long-standing amblyopia.
Methods Study Participants Twenty-three adult amblyopes, mean age: Intervention: A dichoptic custom-made Unreal Tournament video game We have developed a dichoptic version of a commercial first-person-shooter action video game, Unreal Tournament Establishing alignment, fusion and perceptual matching adjustment before gameplay Achieving adequate fusion and alignment is critical for amblyopic individuals when playing a dichoptic game.
Progression of difficulty during gameplay The goal of the game is to slay as many bots computer controlled players or opponent as possible without getting killed, within a certain time limit. Orientation discrimination task with Gabor target An adaptive Gabor discrimination task, similar to the ones employed in perceptual learning studies, was presented to the AE during game play.
Additional Suppression checks during gameplay In order to minimize the chances of suppression during dichoptic game play, we implemented frequent suppression checks. References Levi, D. Article Google Scholar Worth, C.
Article Google Scholar Maehara, G. Article Google Scholar Mansouri, B. Article Google Scholar Ding, J. Article Google Scholar Hess, R. Article Google Scholar Harrad, R. Article Google Scholar Bi, H. Article Google Scholar Birch, E. Article Google Scholar Gambacorta, C. Article Google Scholar Li, J.
Article Google Scholar Zhou, J. Article Google Scholar Zhang, P. In preliminary studies, these video games have improved vision in both children and adults- and at a much faster rate than the typical patching treatment.
Many patients improved their depth perception- and a few even saw in 3D for the first time! Vision therapy is a great amblyopia treatment option because it treats all the weaknesses of the lazy eye, not just the reduction in visual acuity. Amblyopic eyes also have difficulty tracking, focusing, and processing visual information. The amblyopic visual system also has reduced depth perception. Vision therapy retrains pathways in the brain to improve vision the amblyopic eye, and teaches the brain to use both eyes together as a team.
This research is very exciting news for children and adults with amblyopia. Historically, amblyopia was not treated in adults because scientists believed neuroplasticity did not exist in the adult brain, and clinical trials of patching in adults did not show much improvement in visual acuity.
Attempting amblyopia treatment in adults is worthwhile because the good eye is at an increased risk for injuries and eye disease. The results of their ongoing research could significantly influence future amblyopia treatment guidelines. Dichoptic training enables the adult amblyopic brain to learn. Current Biology 8 : A new binocular approach to the treatment of amblyopia in adults well beyond the critical period of development.
Restorative Neurology and Neuroscience Biomed Research International Quantitative measurement of interocular suppression in children with amblyopia. Vision Res How best to assess suppression in patients with high anisometropia. Stimuli were random-dot kinematograms, which consisted of a population of signal dots, all moving in a common direction, and a population of noise dots, that moved randomly.
The luminance modulation Michelson contrast and hence the visibility of the dots could be varied by increasing the luminance of the dots, with respect to the background, according to the following equation:. It is evident that amblyopic participants had a significantly larger imbalance between the eyes than the control participants i.
The fact that control participants did have a small contrast offset reflects the sensitivity of this test to eye dominance. These results demonstrate that once balanced, the amblyopic participants performed no worse, in fact a little better, than the control observers; however, thresholds across the groups were generally comparable. The thresholds of amblyopic participants were very similar to those in previous reports using related techniques in a group of observers with amblyopia 13 and a group of observers with normal binocular vision who were shown stimuli of equal contrast to both eyes.
Figure 1. View Original Download Slide. The contrast presented to the fellow or dominant eye to achieve balanced performance on the motion coherence task between the two eyes i.
These analyses indicate that the patient's age did not systematically influence these variables. As such, the observers with amblyopia were treated as a single group in subsequent analyses. To compare the balance point test with clinical tests of suppression, we correlated the results of the Worth 4-Dot test and the modified Bagolini striated lenses test with the balance point contrast.
The near and far results for the Worth 4-Dot test were combined to give a score from 0 no suppression for either test to 4 full suppression on both tests.
This finding demonstrates that the larger the difference in contrast between the two eyes that is necessary for normal binocular combination of motion signals i. Figure 2. The relationship between the contrast presented to the fellow fixing eye at the balance point and suppression on the Worth 4-Dot test A and the modified Bagolini striated lenses test B.
Higher numbers on both the Worth and Bagolini tests x -axis are indicative of greater suppression. Smaller contrast values for the balance point y -axis are indicative of greater suppression, as a larger imbalance between the eyes is required for binocular combination to occur. A Interval data on the abscissa and ordinal data on the ordinate axis. The statistical analysis for this comparison was nonparametric and conducted on the ranked data using Spearman's rho.
These correlations are shown in Figure 3. To assess whether the relationship between these two variables and the contrast at balance point differed among anisometropic, mixed, and strabismic amblyopes, we performed a univariate general linear model analysis on the contrast at balance point data with amblyopia type anisometropic versus mixed versus strabismic , acuity difference between the eyes, and stereo sensitivity as covariates.
There was no significant interaction between amblyopia subtype and stereo sensitivity, suggesting that the effect of stereo sensitivity did not vary across the different amblyopia subtypes.
To explore the interocular visual acuity difference and amblyopia subtype interaction further, we correlated interocular visual acuity difference with balance point contrast separately for each amblyopia subtype. Figure 3. The relationship between contrast in the fellow fixing eye at the balance point and stereo sensitivity A or acuity difference between the eyes B. Dashed lines : the best linear fit to the data. For stereo sensitivity A the negative correlation shows that the lower the balance point contrast in the fellow fixing eye i.
The positive correlation for acuity difference B demonstrates that the greater the difference between the eyes at balance point contrast, the larger the acuity difference. We have shown that dichoptic motion coherence thresholds can be used to assess sensory ocular dominance in observers with normal binocular vision.
Figure 4. Larger threshold ratios and lower fellow eye contrasts indicate a greater deficit for the amblyopic eye under dichoptic viewing conditions. Next, we assessed whether the amount of suppression was greater in participants who had never received treatment for their amblyopia. Within our sample, 16 anisometropic and 7 strabismic amblyopes had never received treatment, 6 anisometropic and 1 mixed amblyope had received patching only, 6 strabismic and 2 mixed amblyopes had received surgery only, and 4 strabismic and 1 mixed amblyope had received both patching and surgery.
Figure 5 shows the mean contrast for the fellow fixing eye at balance point Fig. Figure 5. Finally, we considered only the participants with strabismic or mixed amblyopia who still had strabismus to assess whether the extent of strabismus was related to the strength of suppression.
The relationship between angle of deviation and suppression is shown in Fig. Exotropes and esotropes are identified in these plots by the use of filled and hollow markers, respectively. Figure 6. The relationship between the angle of strabismus and strength of suppression using the balance point measurement A and the Bagolini method B. The two larger circles indicate overlapping esotrope and exotrope data points. Dashed lines : indicate linear fits to the data.
In this study, we set out to answer the three questions detailed below. How does the new balance point method compare with the current clinical standards Worth 4-Dot test and modified Bagolini test across a clinical population? Using a novel approach involving the measurement of dichoptic motion thresholds for stimuli of different interocular contrast, we show that the degree of suppression is significant in strabismus, anisometropia, and mixed amblyopia, but that there was no significant difference across our clinical sample in the different subgroups i.
We also demonstrate that this new quantitative approach to the measurement of suppression correlates strongly with traditional, albeit qualitative, clinical measures. Finally, we show a significant correlation between the balance point measure and a more abbreviated measurement based on the same principle previously used to quantify sensory dominance in the normal population. What is the relationship between visual losses in amblyopia acuity and stereo and the degree of suppression?
As discussed above, this measure of suppression is in close agreement with standard clinical measures. We found that the degree of suppression measured using this technique significantly correlated with the degree of amblyopia and stereo loss.
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