Modulation of mean luminance improves binocular balance across spatial frequencies in amblyopia.
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ABSTRACT:
SUBMITTER: Min SH
PROVIDER: S-EPMC9249912 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Amblyopia is a visual disorder that originates from the brain. It exhibits no pathology in the eye. Studies have shown that measuring both visual acuity and binocular balance for assessing amblyopia could be more helpful. However, tests that measure binocular balance are time-consuming, often exceeding 30 min. Their long test durations prevent them from being used in the clinic. For this reason, we have developed a quick (i.e., about 7 min) and precise tool that quantitatively measures binocular balance of patients with amblyopia. The new test can capture binocular imbalance that is typically exhibited at high spatial frequency in amblyopes. In addition, it has an excellent test-retest reliability and repeatability between two experimental sessions. We hope that our newly developed test can pave the road for physicians and researchers to better assess and diagnose amblyopia and other visual disorders that disrupt binocular balance beyond the laboratory.
| S-EPMC8733258 | biostudies-literature
Project description:While amblyopia involves both binocular imbalance and deficits in processing high spatial frequency information, little is known about the spatial-frequency dependence of binocular imbalance. Here we examined binocular imbalance as a function of spatial frequency in amblyopia using a novel computer-based method. Binocular imbalance at four spatial frequencies was measured with a novel dichoptic letter chart in individuals with amblyopia, or normal vision. Our dichoptic letter chart was composed of band-pass filtered letters arranged in a layout similar to the ETDRS acuity chart. A different chart was presented to each eye of the observer via stereo-shutter glasses. The relative contrast of the corresponding letter in each eye was adjusted by a computer staircase to determine a binocular Balance Point at which the observer reports the letter presented to either eye with equal probability. Amblyopes showed pronounced binocular imbalance across all spatial frequencies, with greater imbalance at high compared to low spatial frequencies (an average increase of 19%, p < 0.01). Good test-retest reliability of the method was demonstrated by the Bland-Altman plot. Our findings suggest that spatial-frequency dependent binocular imbalance may be useful for diagnosing amblyopia and as an outcome measure for recovery of binocular vision following therapy.
| S-EPMC4658600 | biostudies-other
Project description:Luminance plays a modulating role in the processes of several visual tasks, which in turn provides significant information for the understanding of visual processing. Here, using a binocular phase combination paradigm, we studied the effect of unilateral changes in mean luminance on binocular combination in both normal and amblyopic vision. We found, in normal observers, attenuation of one eye's stimulus luminance with neutral density filters produces binocular phase combination similar to those of amblyopic subjects. Correspondingly, in amblyopic observers, reduction of the fellow eye's stimulus luminance produces binocular phase combination similar to those of normal subjects. These phenomena could be explained by an attenuated contribution of the filtered eye to the binocular phase percept due to reduced gain-control. The findings have major implications both for the study of binocular combination and for amblyopia treatment.
| S-EPMC3684813 | biostudies-other
Project description:Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3%-3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia.
| S-EPMC3577063 | biostudies-literature
Project description:Childhood amblyopia can be treated with binocular games or movies that rebalance contrast between the eyes, which is thought to reduce depth of interocular suppression so the child can experience binocular vision. While visual acuity gains have been reported following binocular treatment, studies rarely report gains in binocular outcomes (i.e., stereoacuity, suppression) in amblyopic children. Here, we evaluated binocular outcomes in children who had received binocular treatment for childhood amblyopia.Data for amblyopic children enrolled in two ongoing studies were pooled. The sample included 41 amblyopic children (6 strabismic, 21 anisometropic, 14 combined; age 4-10 years; ?4 prism diopters [PD]) who received binocular treatment (20 game, 21 movies; prescribed 9-10 hours treatment). Amblyopic eye visual acuity and binocular outcomes (Randot Preschool Stereoacuity, extent of suppression, and depth of suppression) were assessed at baseline and at 2 weeks.Mean amblyopic eye visual acuity (P < 0.001) and mean stereoacuity improved (P = 0.045), and mean extent (P = 0.005) and depth of suppression (P = 0.003) were reduced from baseline at the 2-week visit (87% game adherence, 100% movie adherence). Depth of suppression was reduced more in children aged <8 years than in those aged ?8 years (P = 0.004). Worse baseline depth of suppression was correlated with a larger depth of suppression reduction at 2 weeks (P = 0.001).After 2 weeks, binocular treatment in amblyopic children improved visual acuity and binocular outcomes, reducing the extent and depth of suppression and improving stereoacuity. Binocular treatments that rebalance contrast to overcome suppression are a promising additional option for treating amblyopia.
| S-EPMC5839256 | biostudies-literature
Project description:Steady state visual evoked potential (SSVEP)-based brain computer interface (BCI) has advantages of high information transfer rate (ITR), less electrodes and little training. So it has been widely investigated. However, the available stimulus frequencies are limited by brain responses. Simultaneous modulation of stimulus luminance is a novel method to resolve this problem. In this study, three experiments were devised to gain a deeper understanding of the brain response to the stimulation using inter-modulation frequencies. First, luminance-based stimulation using one to five inter-modulation frequencies was analyzed for the first time. The characteristics of the brain responses to the proposed stimulation were reported. Second, the motion-based stimulation with equal luminance using inter-modulation frequencies was also proposed for the first time. The response of the brain under these conditions were similar to that of luminance-based stimulation which can induce combination frequencies. And an elementary analysis was conducted to explain the reason of the occurrence of combination frequencies. Finally, the online test demonstrated the efficacy of our proposed two stimulation methods for BCI. The average ITRs reached 34.7836 bits/min and 39.2856 bits/min for luminance-based and motion-based stimulation respectively. This study demonstrated that the simultaneous modulation of stimulus luminance could extend to at least five frequencies to induce SSVEP and the brain response to the stimulus still maintained a certain positive correlation with luminance. And not only luminance-based stimulation, but also motion-based stimulation with equal luminance can elicit inter-modulation frequencies to effectively increase the number of targets for multi-class SSVEP.
| S-EPMC5687765 | biostudies-literature
Project description:Recent experimental evidence supports a role for binocular visual experience in the treatment of amblyopia. The purpose of this study was to determine whether repeated binocular visual experience with dichoptic iPad games could effectively treat amblyopia in preschool children.A total of 50 consecutive amblyopic preschool children 3-6.9 years of age were assigned to play sham iPad games (first 5 children) or binocular iPad games (n = 45) for at least 4 hours per week for 4 weeks. Thirty (67%) children in the binocular iPad group and 4 (80%) in the sham iPad group were also treated with patching at a different time of day. Visual acuity and stereoacuity were assessed at baseline, at 4 weeks, and at 3 months after the cessation of game play.The sham iPad group had no significant improvement in visual acuity (t4 = 0.34, P = 0.75). In the binocular iPad group, mean visual acuity (plus or minus standard error) improved from 0.43 ± 0.03 at baseline to 0.34 ± 0.03 logMAR at 4 weeks (n = 45; paired t44 = 4.93; P < 0.0001). Stereoacuity did not significantly improve (t44 = 1.35, P = 0.18). Children who played the binocular iPad games for ?8 hours (?50% compliance) had significantly more visual acuity improvement than children who played 0-4 hours (t43 = 4.21, P = 0.0001).Repeated binocular experience, provided by dichoptic iPad game play, was more effective than sham iPad game play as a treatment for amblyopia in preschool children.
| S-EPMC4346708 | biostudies-literature
Project description:Amblyopia is associated with a range of well-known visual spatial deficits, which include reduced contrast sensitivity, spatial distortions, interocular suppression, and impaired stereopsis. Previous work has also pointed to deficits in processing dynamic visual information, but it is unknown whether these deficits influence performance under binocular conditions. We examined the effects of temporal modulation on contrast sensitivity and binocular interactions in a preliminary study of 8 adults with amblyopia and 14 normally-sighted control subjects. For each observer, we measured interocular balance and stereopsis thresholds with binocular flicker across a range of four temporal (0, 4, 7.5, and 12?Hz) and spatial (1, 2, 4, and 8?cpd) frequencies. Interocular balance was estimated by varying the relative contrast of dichoptic letter pairs to produce perceptual reports of each letter with equal frequency, and stereopsis thresholds were measured by determining the minimum disparity at which subjects identified a front-depth target with 75% accuracy. Consistent with previous findings, we observed greater interocular imbalance and impaired stereoacuity at high spatial frequencies in amblyopes. In contrast, the effects of temporal frequency on performance were smaller: across both groups, interocular imbalance was largest at mid-to-low temporal frequencies, and stereopsis thresholds were unaffected by temporal frequency. Our results suggest that there may be a previously unreported effect of temporal frequency on interocular balance, as well as a possible dissociation between the effects of flicker on interocular balance and stereopsis.
| S-EPMC6726518 | biostudies-literature
Project description:PurposeTo measure binocular interaction in amblyopes using a rapid and patient-friendly computer-based method, and to test the feasibility of the assessment in the clinic.MethodsBinocular interaction was assessed in subjects with strabismic amblyopia (n = 7), anisometropic amblyopia (n = 6), strabismus without amblyopia (n = 15) and normal vision (n = 40). Binocular interaction was measured with a dichoptic phase matching task in which subjects matched the position of a binocular probe to the cyclopean perceived phase of a dichoptic pair of gratings whose contrast ratios were systematically varied. The resulting effective contrast ratio of the weak eye was taken as an indicator of interocular imbalance. Testing was performed in an ophthalmology clinic under 8 mins. We examined the relationships between our binocular interaction measure and standard clinical measures indicating abnormal binocularity such as interocular acuity difference and stereoacuity. The test-retest reliability of the testing method was also evaluated.ResultsCompared to normally-sighted controls, amblyopes exhibited significantly reduced effective contrast (∼20%) of the weak eye, suggesting a higher contrast requirement for the amblyopic eye compared to the fellow eye. We found that the effective contrast ratio of the weak eye covaried with standard clincal measures of binocular vision. Our results showed that there was a high correlation between the 1st and 2nd measurements (r = 0.94, p<0.001) but without any significant bias between the two.ConclusionsOur findings demonstrate that abnormal binocular interaction can be reliably captured by measuring the effective contrast ratio of the weak eye and quantitative assessment of binocular interaction is a quick and simple test that can be performed in the clinic. We believe that reliable and timely assessment of deficits in a binocular interaction may improve detection and treatment of amblyopia.
| S-EPMC4069064 | biostudies-literature
Project description:PURPOSE:To determine the role of Interactive Binocular Treatment (I-BiT™) as a complementary method of patching in amblyopia therapy. METHODS:In this randomized clinical trial study, 50 unilateral amblyopic children (25 male/25 female) between 3 and 10 years with either best corrected visual acuity (BCVA) ?20/30 in the amblyopic eye or a difference of BCVA ? 2 lines between the two eyes were included. They were randomly classified into the case and control groups (25 in each). Patching was recommended in both groups, and cases also received I-BiT™. Cases were asked to play I-BiT™ games through appropriate glasses with conjugate colored filters. Moving and fixed targets were shown to the amblyopic and non-amblyopic eyes, respectively. Playing games was continued 20 min in each session for 5 days a week within one month (total time: 6.6 h). Patching was continued for one month more in both groups to evaluate the continuous effect of I-BiT™. BCVA was measured at baseline, one month after beginning I-BiT™, and one month after cessation of I-BiT™. RESULTS:BCVA of amblyopic eyes in cases and controls were 0.34 ± 0.14 and 0.33 ± 0.17LogMAR at baseline which improved to 0.17 ± 0.14 and 0.26 ± 0.17 at one month, respectively. The difference was significant in each group (p < 0.001 for cases and p = 0.024 for controls) with more improvement in the case group (p < 0.001). One month after cessation of I-BiT™, BCVA difference between the two groups was not statistically significant. There was no case with recurrence of amblyopia. CONCLUSION:Based on our results, I-BiT™ seems to be effective in amblyopia therapy accompanied with patching. We recommend comparing I-BiT™ alone with patching in further studies. ClinicalTrials.gov Identifier: NCT02740725.
| S-EPMC5093783 | biostudies-literature