Abstract
Abstract: :
Purpose: Systematic light stimulation reduces the size of blind areas in patients with brain lesions. We observed topographical patterns of functional recovery over six months of visual restitution training, comparing changes of objective and subjective visual field size. Methods: The size of visual field defects in nineteen patients was determined in perimetric and campimetric tests before visual field training. Additionally, subjects were drawing their visual field border in a standardized chart of the right and left eye. After six months of visual restitution training, diagnostic procedures were repeated. Correlations between objective and subjective visual field size were determined as well as changes in both variables over the treatment period. Topographical patterns of visual field recovery in both tests were analyzed. Results: Subjective visual field size was substantially correlated with perimetric measurements even before training. As detection performance increased in ?objective? visual field tests over training, a decrease of subjective defect size was observed (significant for the left eye). Correlations of subjective and objective visual field size increased during training. The mean decrease of subjective defect size in both eyes was substantially correlated with the increase in campimetric detection performance but just missed significance. Form and size of the scotoma was very accurately represented in most patients, and their drawings also reflected training-induced improvement. Foveal defects were perceived as larger and improvements were more clearly represented in the drawings than peripheral shifts of visual field border. Conclusion: Visual restitution training increases intact visual field size in ?objective? visual field tests but also affects the subjective representation of the defect. Patterns of recovery follow the laws of the cortical magnification factor, and changes of subjective visual field size are weighted by the importance of a visual field region for visual perception. Thus, objective as well as subjective measures of scotoma size reflect the architecture of the visual system.