Improving myopia via perceptual learning: is training with lateral masking the only (or the most) efficacious technique?

Perceptual learning produces an improvement in visual functions such as an increase in visual acuity (VA) and contrast sensitivity in participants with both amblyopia and refractive defects. This improvement has been observed in the presence of lateral masking, which is known to bring about lateral interactions between detectors in early cortical pathways. Improvement has also been revealed in the absence of flankers in healthy individuals and those with amblyopia. This study seeks to understand whether a perceptual training regime really needs to be based on lateral interactions in cases where poor vision is not due to cortical dysfunction, such as myopia. Ten participants with mild myopia (max -2D) were recruited. A battery of tests measuring visual function was administered prior to (pre-test) and following (post-test) the training. The participants carried out an 8-week behavioural training using a single Gabor perceptual learning paradigm, completing a total of 24 sessions. Results indicate that training using a single Gabor protocol results in a VA improvement of 0.16 logMAR. The present study supports the idea that, in the absence of cortical deficits, as is the case in myopia, some sort of compensatory mechanism can take place at the cortical level by means of perceptual learning, resulting in more effective processing of the received blurred input. However, regarding training based on lateral masking, here we found that improvement of visual functions was smaller and limited to VA. This might suggest that training based on lateral masking, which is able to modify the strength of facilitatory and inhibitory lateral interactions, could be more effective for optimal recovery of blurred vision.