Forget ortho-k and atropine drops, tomorrow’s myopes might find success with a pair of brain-exciting electrodes.
Small studies with 30 myopic adult patients and 17 anisometric amblyopic adult patients looked at the effect of undertaking perceptual training while undergoing a certain type of brain stimulation, known as transcranial random noise stimulation (tRNS).
The combination was successful for both types of refractive error, with patients who received the joint procedures showing an average improvement of nearly two LogMAR chart lines, in the research presented at the Visual Sciences Society 2016 conference (13–18 May, Florida).
Paper co-author and University of Padova psychologist, Dr Gianluca Campana, told OT that the study applied a low-intensity alternating current to stimulate the visual areas of the patients’ brains.
“The main effects of this procedure are an increase in neural excitability of that part of the brain and a boosting of neural plasticity,” he explained.
Control groups received just the perceptual training, or just the brain stimulation, Dr Campana said.
“I think the results are quite exciting, especially when we ruled out that training without tRNS, or tRNS without training, could produce similar results,” he emphasised.
Just as excited were the amblyopic patients, Dr Campana said, adding: “I have to say that those with amblyopia were much more enthusiastic about their visual improvements. After all, a mild myope can still put on a pair of glasses, or contact lenses, and have perfect vision, whereas an adult with amblyopia cannot correct their deficit with any optical correction.”
It is thought that, in the myopic patients, the twin procedures enhance the participants’ contrast sensitivity.
Dr Campana highlighted: “This can overcome the blurring due to defocus of the image – something like improving a slightly blurred image with Photoshop.”
The brain-stimulated training was also capable of addressing the dysfunctional connections between brain cells in amblyopic adult patients, he said.
“We are able to induce neural plasticity, that is to change – to strengthen – the connections between these visual neurons,” he explained.
Other research has also found success in similar forms of brain stimulation in treating amblyopia in adults.
Dr Campana’s team is continuing to research the effects of the combination of brain stimulation and training for both types of refractive error. One study assesses whether the visual acuity gains in amblyopic patients lasted up to nine months after treatment.