Vision training with VEP biofeedback in amblyopia after the critical period

Lapajne, Luka; Roškar, Sanja; Pompe, Manca Tekavčič; Svetina, Matija; Jarc-Vidmar, Martina; Hawlina, Marko

doi:10.1007/s10633-020-09774-z

Cited by 4 publications

(2 citation statements)

References 34 publications

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“…The filter bank strategy in training-free methods, such as filter bank CCA (FBCCA) (Chen et al, 2015) and filter bank MSI (FBMSI) (Qin et al, 2021), may be also used to enhance the performance of SSVEP-based visual acuity assessment in future work. In contrast, the subjectspecific training methods with the best performance (Zerafa et al, 2018), requiring training data from the specific user and needing the cost of long and tiring training sessions, such as individual template-based CCA (itCCA) (Bin et al, 2011), combined-CCA (Nakanishi et al, 2014;Wang et al, 2014b), multiway CCA (Zhang et al, 2011), multiset CCA (Zhang et al, 2014b), and task-related component analysis (TRCA) (Nakanishi et al, 2018a), may be more suitable for the situation where the subjects need long-term use of BCI system, such as the vision training with SSVEP biofeedback in amblyopia (Lapajne et al, 2020). Besides, the subject-independent training methods requiring training data from various subjects, providing a good trade-off between training effort and performance (Zerafa et al, 2018), such as transfer template CCA (ttCCA) (Yuan et al, 2015) and combined-tCCA (Waytowich et al, 2016), may be further applied in SSVEP visual acuity assessment.…”

Section: Discussionmentioning

confidence: 99%

Enhancing Performance of SSVEP-Based Visual Acuity via Spatial Filtering

Zheng

Han

et al. 2021

Front. Neurosci.

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The purpose of this study was to enhance the performance of steady-state visual evoked potential (SSVEP)-based visual acuity assessment with spatial filtering methods. Using the vertical sinusoidal gratings at six spatial frequency steps as the visual stimuli for 11 subjects, SSVEPs were recorded from six occipital electrodes (O1, Oz, O2, PO3, POz, and PO4). Ten commonly used training-free spatial filtering methods, i.e., native combination (single-electrode), bipolar combination, Laplacian combination, average combination, common average reference (CAR), minimum energy combination (MEC), maximum contrast combination (MCC), canonical correlation analysis (CCA), multivariate synchronization index (MSI), and partial least squares (PLS), were compared for multielectrode signals combination in SSVEP visual acuity assessment by statistical analyses, e.g., Bland–Altman analysis and repeated-measures ANOVA. The SSVEP signal characteristics corresponding to each spatial filtering method were compared, determining the chosen spatial filtering methods of CCA and MSI with a higher performance than the native combination for further signal processing. After the visual acuity threshold estimation criterion, the agreement between the subjective Freiburg Visual Acuity and Contrast Test (FrACT) and SSVEP visual acuity for the native combination (0.253 logMAR), CCA (0.202 logMAR), and MSI (0.208 logMAR) was all good, and the difference between FrACT and SSVEP visual acuity was also all acceptable for the native combination (−0.095 logMAR), CCA (0.039 logMAR), and MSI (−0.080 logMAR), where CCA-based SSVEP visual acuity had the best performance and the native combination had the worst. The study proved that the performance of SSVEP-based visual acuity can be enhanced by spatial filtering methods of CCA and MSI and also recommended CCA as the spatial filtering method for multielectrode signals combination in SSVEP visual acuity assessment.

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Section: Discussionmentioning

confidence: 99%

Enhancing Performance of SSVEP-Based Visual Acuity via Spatial Filtering

Zheng

Han

et al. 2021

Front. Neurosci.

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“…It was long demonstrated that visual fixation can be improved with auditory feedback in amblyopia [ 29 ]. More recently, functional gain was demonstrated in children and adults undergoing visual training using pattern stimulation associated with auditory feedback [ 30 , 31 ].…”

Section: Introductionmentioning

confidence: 99%

Fixation stability after surgical treatment of strabismus and biofeedback fixation training in amblyopic eyes

et al. 2021

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Background Visual fixation may be affected in amblyopic patients and, moreover, its stability may be associated with the effects of amblyopic treatments on visual performance in patients with strabismus. Therefore, fixation stability is a relevant biomarker that might predict the recurrence of amblyopia after a therapeutic intervention. Microperimetric biofeedback fixation training (BFT) can stabilize visual fixation in adult patients with central vision loss. It was the purpose of the present study to evaluate the effects of BFT on fixation stability in adult amblyopic patients after surgical intervention to treat strabismus. Methods Participants were 12 patients with strabismus (mean age = 29.6 ± 8.5 years; 6 females) and 12 healthy volunteers (mean age = 23.8 ± 1.5 years; 9 females). The protocol included ophthalmological and microperimetric follow-ups to measure fixation stability and macular sensitivity. BFT was applied monocularly to four amblyopic eyes either on the spontaneous preferential retinal locus or to a fixation area closer to the anatomical fovea after surgical treatment of strabismus. Results Baseline measurements showed significantly altered microperimetric average threshold in amblyopic eyes compared to fellow eyes (p = 0.024) and compared to control eyes (p < 0.001). Fixation was unstable in amblyopic eyes compared to control eyes (p < 0.001). Fixation stability did not significantly change after surgical alignment of strabismus (p = 0.805). BFT applied to operated eyes resulted in a more stable fixation with improvements of about 50% after three months of training. Conclusions Fixation stability improvements following BFT highlight its potential use in adult amblyopic eyes after the surgical alignment of the strabismus. Future investigations may also consider applying this method in combination with standard treatments to improve vision in amblyopic patients.

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Evaluation of fixation characteristics in amblyopia using microperimetry

et al. 2023

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Purpose: To evaluate xation characteristics in amblyopia using macular analyzer integrity assessment (MAIA) microperimetry and to investigate the factors affecting xation stability.Methods: This prospective, cross-sectional study enrolled a total of 58 amblyopic patients (8-55 years old). Average threshold macular sensitivity (AT) and xation characteristics were assessed using the MAIA microperimetry (CenterVue, Padova, Italy). Two Bivariate contour ellipse areas (BCEA) xation indices (63% and 95% proportional values) and the percentage of xation points within 1° and 2° from the fovea (P1 and P2) were used to assess xation stability.Results: AT and xation stability parameters (P1, P2, BCEA 63%, BCEA 95%) were worse in the amblyopic eyes (p<0.05, for all). There was a positive correlation between BCVA, and AT, and P2, and negative correlations between BCVA, and BCEA 63%, and BCEA 95%. The eccentric xation was 48% in the amblyopic eyes (25% in anisometropic group, 52% in strabismic group, 69% in combined group) and 32% in the non-amblyopic eye. The preferred xation eccentricity in amblyopic eyes was signi cantly greater than the non-amblyopic eyes (p=0.004), and there was a negative correlation between preferred xation eccentricity and BCVA (p=0.012, r=-.327).Conclusions: Our data showed a decrease in xation stability, a positive correlation between xation stability and BCVA, and a negative correlation between preferred xation eccentricity and BCVA in amblyopic eyes. This result made us think that microperimetric acoustic biofeedback xation training, which is used to increase xation stability in low vision rehabilitation, may also be a useful approach in amblyopia.

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Vision training with VEP biofeedback in amblyopia after the critical period

Cited by 4 publications

References 34 publications

Enhancing Performance of SSVEP-Based Visual Acuity via Spatial Filtering

Enhancing Performance of SSVEP-Based Visual Acuity via Spatial Filtering

Fixation stability after surgical treatment of strabismus and biofeedback fixation training in amblyopic eyes

Evaluation of fixation characteristics in amblyopia using microperimetry

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