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D.A. Poggel, E.M. Mueller-Oehring, J. Gothe, S. Kenkel, E. Kasten, B.A. Sabel; Patients With Visual Field Defects Experience Pseudo-Hallucinations During Spontaneous and Training-Induced Recovery . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4096.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Visual pseudo-hallucinations have been observed in 10-15% of patients suffering from visual system lesions during spontaneous recovery. We investigated whether those illusions also occur during visual restitution training (VRT), a computer-based treatment for the detection of white light stimuli at the visual field border. The phenomenology of training-induced illusions was compared to pseudo-hallucinations during spontaneous recovery. Methods: In a prospective study, perimetric baseline examinations before and after a period of six months of VRT were performed as well as repeated interviews in a group of 19 patients with post-genicular lesions performed. A separate group of 119 patients with different pre- and post-genicular lesions who had done VRT answered a questionnaire on pseudo-hallucinations after training. Results: In the prospective trial, 52.6% of the patients had experienced mainly complex visual illusions during spontaneous recovery (moving, colored, geometrical forms, real objects, or scenes). During training, significantly more patients reported pseudo-hallucinations, but only those who had perceived those phenomena after the lesion. Training-induced illusions were usually simple (white flashes or spots). They were temporally and topographically associated with functional recovery. In the larger sample, 36.4% had perceived pseudo-hallucinations in the context of the lesioning event, and 15.4% reported training-induced illusions. Pseudo-hallucinations during treatment occurred significantly more often in those patients who reported an increase of visual field size. Conclusions:Most likely, visual illusions reflect spontaneous activity in (partially) lesioned brain areas which may be the basis for functional recovery. After a lesion, large areas of visual cortex show spontaneous activation, generating mostly complex illusions. During VRT, V1 is specifically activated, triggering more simple pseudo-hallucinations associated with training-induced visual field increase.
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