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Simon Clavagnier, Benjamin Thompson, Robert Hess; Long lasting contrast sensitivity improvement after daily cTBS sessions in adults with amblyopia.. Journal of Vision 2012;12(9):1363. doi: 10.1167/12.9.1363.
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There is increasing evidence of residual brain plasticity in adults well beyond the conventional critical period for visual development. Indeed, although traditional patching therapy to treat amblyopia is not effective above the age of 10 years, single session of 10Hz repetitive transcranial magnetic stimulation (rTMS) of the primary visual cortex in adults was shown to temporally improve visual performances (Thompson et al, Current Biology, 2008). We wanted to know whether continuous theta burst stimulation (cTBS) of the visual cortex could also be effective in restoring function in adult amblyopes and whether repeated daily application could result in stronger and longer-lasting effects. We tested 5 adult amblyopes (18-60 years). Contrast sensitivity was measured before and after cTBS using high (hSF) and low (lSF) spatial frequency stimuli. cTBS consisted in 600 pulses at 41% MSO intensity, delivered at 50Hz as bursts of 3 pulses repeated 5 times a second for 40 seconds on the visual cortex. Whereas no effect was observed on the contrast sensitivity of the fellow eye either at lSF or at hSF, or on the contrast sensitivity of the amblyopic eye at lSF, contrast sensitivity in the amblyopic eye at hSF improved, the effect becoming statically significant 30 min after the stimulation (t4=3.59, p<0.05). Four participants completed 5 successive days of that stimulation protocol and, as a group, showed a cumulative improvement across sessions with asymptotic recovery occurring after 2 daily sessions of stimulation (chi² = 6.00, p<0.05). We retested 3 subjects at various times after the final period of stimulation and found the functional recovery to remain stable over a period of up to 78 days. Having the advantage of being rapid to administer and using low intensities, cTBS appears well-suited for further investigation into the potentially beneficial effects of rTMS on visual function in adults with amblyopia.
Meeting abstract presented at VSS 2012
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