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Vision restoration therapy (VRT) has been the subject of considerable controversy,1–3 and with Horton’s latest editorial3 it has now turned rather personal. The editorial is filled with numerous inaccuracies and misrepresentations and this cannot go unanswered. Just as a scientific debate should not focus on fiction but on facts, comments by critics must be evaluated with the same rigor as the original work itself. Only by keeping track of all of the scientific evidence rather than by a personal and limited review of some selected facts will we get closer to the truth.
Firstly, it is a fundamental misrepresentation by Horton that we are trying to “salvage neurons” at the fringe of a lesion. Rather, we believe that VRT activates surviving neurons in areas of residual vision (ARVs)—that is, areas that are partially damaged.4–7 Repetitive use through daily training increases neuronal activation,8 which is greatly enhanced by attentional processes.9 No neuron is “salvaged.”
It is correct that at the time Horton wrote his editorials no one had published studies on eye movements. But since then the first eye movement studies have been published in abstract form. It actually turns out that eye movements, when measured with an eye tracker, are not altered after VRT.10 There is also other indirect evidence, which is incompatible with the hypothesis that eye movements explain visual field improvements:
Fixation performance in standard automated perimetry is an accepted quality control measure and our patients typically show >90% stable fixation, which is measured by counting the …
Competing interests: BAS is a shareholder of and consultant to NovaVision, the manufacturer of vision restoration therapy (VRT). NovaVision has also supported research studies conducted in the laboratory of BAS.
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