Vision training with VEP biofeedback in amblyopia after the critical period.
PURPOSE
The purpose of this study was to investigate the benefits of vision training with visual evoked potentials (VEP) biofeedback in amblyopia after the critical period in 8 to 17-year (11.5 ± 3.1) old children.


METHODS
Ten participants with monocular amblyopia after the critical period underwent a 10-week, 20-session vision training program with the Retimax Vision Trainer device. During each session, the participants were instructed to be as focused as possible onto the fixation point in the middle of the screen. The size of the fixation point and the pitch of the background sound were changing according to VEP parameters and thus provided the participants real-time feedback of their visual performance.


RESULTS
The mean BCVA improvement across our group was 0.12 LogMAR (p < 0.01). There was also a significant increase in contrast sensitivity to the FACT chart across all spatial frequencies (all p < 0.05). Electrophysiologic data revealed higher steady-state visual evoked potentials (SS-VEP) amplitudes and correspondingly lower fixation point values in the last 2 weeks of training compared to the first 2 weeks (both p < 0.01). Due to unexplainably low VEP amplitude levels in later trainings compared to those in the beginning in two participants, we have not found a significant correlation between the increase in BCVA and the increase in SS-VEP amplitude (p = 0.88). At the follow-up at 2 and 12 months following the end of training, both BCVA and contrast sensitivity remained within the levels achieved at the end of training. In some participants, however, no improvement of BCVA was observed.


CONCLUSIONS
The tested vision training approach demonstrates modest but stable improvement of psychophysical parameters as well as objective characteristics in amblyopia after the critical period. Real-time SS-VEP can be used as an objective parameter to monitor participants' attention during vision training stimulation.
['Lapajne|Luka|L|0000-0003-3856-8227', 'Roškar|Sanja|S|', 'Tekavčič Pompe|Manca|M|', 'Svetina|Matija|M|', 'Jarc-Vidmar|Martina|M|', 'Hawlina|Marko|M|']
D000293:Adolescent D000550:Amblyopia D002648:Child D015350:Contrast Sensitivity D004596:Electroretinography D005074:Evoked Potentials, Visual D005260:Female D006801:Humans D008297:Male D058765:Neurofeedback D010775:Photic Stimulation D014787:Vision Tests D015354:Vision, Low D014792:Visual Acuity
Vision training Amblyopia Visual evoked potentials Attention Visual rehabilitation