Abstract
BackgroundThe efficacy of treatment in hemianopic patients to restore missing vision is controversial. So far, successful techniques require laborious stimulus presentation or restrict improvements to selected visual field areas. Due to the large number of brain-damaged patients suffering from visual field defects, there is a need for an efficient automated treatment of the total visual field.MethodsA customized treatment was developed for the reaction perimeter, permitting a time-saving adaptive-stimulus presentation under conditions of maximum attention. Twenty hemianopic patients, without visual neglect, were treated twice weekly for an average of 8.2 months starting 24.2 months after the insult. Each treatment session averaged 45 min in duration.ResultsIn 17 out of 20 patients a significant and stable increase of the visual field size (average 11.3° ± 8.1) was observed as well as improvement of the detection rate in the defective visual field (average 18.6% ± 13.5). A two-factor cluster analysis demonstrated that binocular treatment was in general more effective in augmenting the visual detection rate than monocular. Four out of five patients with a visual field increase larger than 10° suffered from hemorrhage, whereas all seven patients with an increase of 5° or less suffered from infarction. Most patients reported that visual field restoration correlated with improvement of visual-related activities of daily living.ConclusionRehabilitation treatment with the Lubeck Reaction Perimeter is a new and efficient method to restore part of the visual field in hemianopia. Since successful transfer of treatment effects to the occluded eye is achieved under monocular treatment conditions, it is hypothesized that the damaged visual cortex itself is the structure in which recovery takes place.
Highlights
The efficacy of treatment in hemianopic patients to restore missing vision is controversial
Zihl and von Cramon [2,3] report that the repetitive presentation of threshold stimuli in the transition zone between the intact and defective visual field (VF), or the saccadic localization of targets presented within the anopic field may result in increased VF up to 27° (a) and 48° (b) of visual angle, respectively
The authors claim that sequential suprathreshold stimulus presentations in 150 training sessions within the defective VF resulted in an average increase of detection rate of 29% in post-chiasmatic and 74% in optic nerve patients, when diagnosed with static perimetry
Summary
The efficacy of treatment in hemianopic patients to restore missing vision is controversial. Due to the large number of brain-damaged patients suffering from visual field defects, there is a need for an efficient automated treatment of the total visual field. Journal of NeuroEngineering and Rehabilitation 2007, 4:31 http://www.jneuroengrehab.com/content/4/1/31 In some of these patients, there may be spontaneous recovery of vision loss, usually within the first weeks or months after the incident [1]. Recent evidence in favor of treatment effects, derives from an attempt to reduce VF defects in patients with post-chiasmatic and optic nerve injuries by using a personal computer monitor for stimulation [5]. The authors claim that sequential suprathreshold stimulus presentations in 150 training sessions within the defective VF resulted in an average increase of detection rate of 29% in post-chiasmatic and 74% in optic nerve patients, when diagnosed with static perimetry. Support for the recovery hypothesis is given by earlier studies in primates, demonstrating that after discrete striate cortex ablations, a decrease of the scotoma size was obtained by visual discrimination testing as a training method or by saccadic eye movement training [6,7,8,9]
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