Related Experiment Video
Updated: Jul 15, 2026
07:12
A Gaze-Contingent Display Framework for Perceptual Learning Research with Simulated Central Vision Loss
Published on: April 11, 2025
Visual hallucinations during spontaneous and training-induced visual field recovery
D A Poggel1, E M Müller-Oehring, J Gothe
1Institute of Medical Psychology, Otto-von-Guericke University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany. dapoggel@bu.edu
Neuropsychologia
|April 17, 2007
Summary
Visual hallucinations can occur during vision restoration therapy (VRT) and spontaneous recovery after visual system lesions. These hallucinations may indicate brain plasticity and functional recovery in visual pathways.
Area of Science:
- Neuroscience
- Ophthalmology
- Neurorehabilitation
Background:
- Visual hallucinations are reported following post-geniculate visual system lesions.
- Spontaneous recovery of visual functions is often associated with these hallucinations.
Purpose of the Study:
- To investigate visual hallucinations during spontaneous recovery.
- To determine if hallucinations re-emerge during vision restoration therapy (VRT).
Main Methods:
- Prospective study of 19 patients with post-geniculate lesions and homonymous visual loss.
- Retrospective study of 121 patients using questionnaires and drawings of hallucinations.
- Visual field size measured before and after 6 months of VRT.
Main Results:
- Hallucinations (colors, objects, motion) occurred post-lesion and subsided with spontaneous recovery.
- Hallucinations re-emerged during VRT, predominantly simple, unformed types (phosphenes, spots).
- Hallucinations were linked to large visual field border shifts and occurred in blind areas with residual vision.
Conclusions:
- Hallucinations may signify functional recovery in partially lesioned brain areas.
- Colored/formed hallucinations suggest higher visual area activation; simple hallucinations indicate primary visual cortex recovery during VRT.
- Visual hallucinations can serve as functional indicators of visual system plasticity, not merely pathological symptoms.
Related Concept Videos
01:12Visual Agnosia
Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round end"...
01:24Color Vision
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.