Bernhard A. Sabel

Computer-based training for the treatment of partial blindness

Partial blindness after brain injury has been considered non-treatable. To evaluate whether patients with visual-field defects can profit from computer-based visual restitution training (VRT), two independent clinical trials were conducted using patients with optic nerve (n = 19) or post-chiasmatic brain injury (n = 19). In post-chiasma patients, VRT led to a significant improvement (29.4%) over baseline in the ability to detect visual stimuli; in optic nerve patients, the effects were even more pronounced (73.6% improvement). Visual-field enlargements were confirmed by the observation of a visual-field expansion of 4.9°–5.8° of visual angle and improved acuity in optic nerve patients. Ninety five percent of the VRT-treated patients showed improvements, 72.2% confirmed visual improvements subjectively. Patients receiving a placebo training did not show comparable improvements. In conclusion, VRT with a computer program improves vision in patients with visual-field defects and offers a new, cost-effective therapy for partial blindness.

Does visual restitution training change absolute homonymous visual field defects? A fundus controlled study

Aim: To examine whether visual restitution training (VRT) is able to change absolute homonymous field defect, assessed with fundus controlled microperimetry, in patients with hemianopia. Methods: 17 patients with stable homonymous visual field defects before and after a 6 month VRT period were investigated with a specialised microperimetric method using a scanning laser ophthalmoscope (SLO). Fixation was controlled by SLO fundus monitoring. The size of the field defect was quantified by calculating the ratio of the number of absolute defects and the number of test points; the training effect E was defined as the difference between these two ratios before and after training. A shift of the entire vertical visual field border by 1° would result in an E value of 0.14. Results: The mean training effect of all right eyes was Eu200a=u200a0.025 (SD 0.052) and all left eyes Eu200a=u200a0.008 (SD 0.034). In one eye, a slight non-homonymous improvement along the horizontal meridian occurred. Conclusions: In one patient, a slight improvement along the horizontal meridian was found in one eye. In none of the patients was an explicit homonymous change of the absolute field defect border observed after training.

Visual field enlargement after computer training in brain-damaged patients with homonymous deficits: an open pilot trial

Brain damage is often accompanied by homonymous hemianopia, but few therapeutic approaches exist for visual field deficits. In this open pilot study we describe a computerized training program which may possibly reduce the size of the blind visual field in patients with homonymous visual field deficits. Various stimuli to test light perception and discrimination of colors and shapes were presented on a monitor which permitted the examination or training of the central section of the visual field up to about 25° vertical and 40° horizontal eccentricity. Eleven patients trained at home for 1 h each day for a total of 80-300 h. Their results were compared with those of three patients who opted not to participate in the training procedure or those with very little therapy. These latter subjects had a slight decrease in the visual field size after about 1 year. In contrast, the treatment group displayed a reliable enlargement of visual field size. This was revealed by a significant improvement in the detection of small light stimuli, an increase in the ability to discriminate colors and a minor, but notable, improvement of shape discrimination in the blind areas of the visual field. Additional training of shape recognition led to further improvement of shape discriminations, even when the patients trained with very different kinds of shapes, e.g. lines or letters. Outcome depended on age of the patients and the size of the lesion, but it was independent of on-set of treatment and cause of the lesion. Only two of the 11 patients with treatment showed no significant improvement. This study suggests that regular home training of the blind visual field with computer-controlled stimuli may lead to improvement in vision. However, because of the following methodological limitations results are only preliminary: (1) the trial did not contain a true placebo group, (2) the patients were not assigned randomly to a control or treatment condition, (3) the lack of defined inclusion criteria considerably increased the variance in neuropsychological performance, (4) because the experimental design was not double blind, experimenter bias cannot be ruled out, and (5) the conditions of the home training could not be standardized. The results warrant a larger randomized, double-blind controlled trial.

Restoration of vision by training of residual functions

A new paradigm emerges: visual field defects after optic nerve or brain injury are partially reversible. Using high-resolution visual field tests, areas of residual vision can be identified which are characterized by impaired vision (relative defect) with some residual capacities. By repetitively stimulating these partially damaged areas with daily computer-based visual restitution training it is now possible to enlarge the visual field. Average border shifts of 5° (range, 0 to 20°) have been found in clinical trials, and training is effective even when started years after the injury. Visual restitution training is useful for the treatment of patients with stroke, head injury, or partial optic nerve damage, as long as the patient presents some residual vision. The improved vision is maintained in most patients after training is discontinued. Brain plasticity is likely to provide the substrate for restoration of vision, opening new opportunities to treat partial blindness, which has been considered irreversible.

Vision restoration therapy

Expanding our viewnnWe have followed with interest the discussion ignited by the paper by Reinhard et al 1 by way of editorial comments from Horton2 and Plant.3 As co-authors of the paper by Reinhard et al 1 and collaborators on that study, we have no objections to the data as presented. However, Horton’s interpretation that these data indicate that “no therapeutic intervention … can correct effectively the underlying visual field deficit” after post-chiasmatic injury is not supported by current scientific evidence. On the contrary, a comprehensive and critical review of the literature reveals that there is a sound scientific basis for recommending vision restoration therapy (VRT) for some patients with hemianopia.nnThe Reinhard study1 used scanning laser ophthalmoscopy (SLO) to evaluate visual fields before and after a 6 month course of VRT and found no change in the size of the blind field detected by this methodology. An important point well taken by Horton is that rather than relying on the VRT computer based tests alone, it would be “more compelling if visual field improvements could be demonstrated with any standard clinical perimeter.” Although not reported in the Reinhard article, the same patients were also tested by two other perimetric methods: the Tubingen automated perimeter (TAP) and high resolution perimetry (HRP, which is a campimetric visual field test).4 We acknowledge that Horton did not have access to this important information which was in press at the time. We believe that not considering these other perimetric data could lead to incorrect conclusions. Even before VRT began, the SLO border was already located significantly closer to the vertical midline than the absolute TAP and HRP borders (fig 1). After VRT, the SLO border was unchanged, but the absolute TAP and HRP borders had significantly shifted, confirming improvement …

Contour-integration deficits on the intact side of the visual field in hemianopia patients.

OBJECTIVEnVisual impairments in hemianopia are thought to be exclusively caused by the reduced visual field size. However, the primary lesion may affect the contralateral hemisphere through damage of interhemispheric projections. The question therefore arises if the presumed intact hemifield is perceptually impaired.nnnMETHODSnThree hemianopia patients and three matched controls carried out a Yes/No figure detection task with their intact side of the visual field. The figure (square) contours were composed of non-contiguous Gabor patches embedded in a random patch array of different background densities (low, delta=2; high, delta=1). Response accuracy and reaction times were recorded.nnnRESULTSnA temporal-parietal patient revealed figure detection impairments, with accuracy rate, 77% (delta=2) and 53% (delta=1), below compared control values. An occipital patient was comparable to his match: 99% (delta=2); 84% (delta=1). Both patients exhibited frequent false alarms to random patterns and required longer presentation times to perform the task. In the third patient, with optic tract lesion, figure detection was nearly normal at low density (92%, delta=2) but impaired at noisy background (62%, delta=1).nnnCONCLUSIONnThe intact visual field in hemianopes is impaired in detection of incomplete figures embedded in a noisy background. This deficit may be caused by damage to higher visual centers and/or loss of interhemispheric interactions.

Restoration of vision III: soma swelling dynamics predicts neuronal death or survival after optic nerve crush in vivo.

Predicting neuron death or survival after axonal injury is important in neurotrauma research. We now used in vivo confocal neuroimaging microscopy to repeatedly visualize retinal ganglion cells after optic nerve crush and studied their morphological alterations and ultimate fate. An intracollicular injection of a retrograde fluorescent tracer was made before or after optic nerve crush. Retinal ganglion cell sizes were then determined at different time points up to post-surgery day 75. Cell death was inevitable when soma swelling was fast and massive (86% above baseline or higher), but when it was slower and moderate (32% above baseline) long-term neuron survival could be predicted with high accuracy as early as post-operative day 5. Moderate swelling continued until day 15 (64%) and after about 3 weeks these cells started shrinking again, as a sign of recovery. We propose that moderate soma swelling is an adaptive rather than pathogenic post-traumatic reaction to axonal injury.

Vision restoration therapy and raising red flags too early

form. It actually turns out that eye movements, when measured with an eye tracker, are not altered after VRT. There is also other indirect evidence, which is incompatible with the hypothesis that eye movements explain visual field improvements: N 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 number of hits at fixation. Because this does not change after VRT (it usually improves slightly, see Kasten et al, Poggel et al, Reinhard et al, Mueller et al, and Sabel et al) it is unlikely that patients moved their eyes

Long-term learning of visual functions in patients after brain damage

PURPOSEnSystematic vision restoration training has been shown to improve the detection performance of brain-damaged patients with visual-field defects. So far, patients have been trained daily up to 6 months. We wished to determine whether intensive long-term training of 12 months further increases visual detection abilities.nnnMETHODSnRetrospective comparison of 17 patients with visual-field defects using vision restoration training for 12 months with a group of patients training for 6 months. Computer-based home training was completed for 6 months (about 195,000 stimuli presentations) or for 12 months (about 390,000 stimuli presentations). Visual fields were measured at baseline with Rodenstock Perimat 206 (monocular) at 90 degrees eccentricity and at 54 degrees eccentricity with high resolution perimetry (HRP) (binocular) after 6 months (post-6) and after 12 months (post-12) of training.nnnRESULTSnNear-threshold perimetry revealed minor training effects, beyond 6 months, of 3.5% (p=0.099) in the right eye and of 1.5% (p=0.57) in the left eye. No effects of long-term training were evident in above threshold testing (0.8% detection improvement, n.s.).nnnCONCLUSIONSnLearning to detect above-threshold stimuli in patients with post-retinal lesions is completed after 6 months of practice with only marginal improvements thereafter. Near-threshold testing reveals that peripheral areas of the visual-field benefit from long-term training even if they are not trained.

Zerebral bedingte Gesichtsfelddefekte aus Patientensicht

ZusammenfassungHintergrundPatienten mit visuellen Beeinträchtigungen werden nicht nur objektiv perimetrisch, sondern auch mit Fragebögen zur Lebensqualität untersucht. Die vorliegende Studie soll erstmalig allgemeine (health-related quality of life, hQoL) und sehspezifische Lebensqualität (vision-related quality of life, vQoL) in einer Stichprobe zerebral geschädigter Patienten mit Gesichtsfelddefekten beschreiben.Material und MethodenDer National Eye Institute – Visual Function Questionnaire (NEI-VFQ, vQoL) und der SF-36-Fragebogen zum Gesundheitszustand (hQoL) wurden an einer Stichprobe von 24 Patienten ca. 2xa0Jahre nach Auftreten des Gesichtsfelddefektes angewandt. Gesichtsfelddefekte wurden perimetrisch und mit einer überschwelligen kampimetrischen Methode erhoben. Die zentrale Sehschärfe wurde mittels Landolt-Ringen gemessen.ErgebnisseDie sehspezifischen Beeinträchtigungen im NEI-VFQ fielen nicht nur gegenüber einer erkrankungsfreien Gruppe, sondern auch im Vergleich mit anderen nicht zerebral geschädigten Patientengruppen mit visuellen Defiziten größer aus. Die mit dem SF-36 erhobene allgemeine Lebensqualität war jedoch nicht geringer als in den Vergleichsstichproben. Zwischen dem Gesichtsfelddefekt und den NEI-VFQ-Skalen konnten mittlere bis hohe Rangkorrelationen nachgewiesen werden. Mit dem SF-36 korrelierte die Größe des Gesichtsfelddefektes nur gering.FazitDer NEI-VFQ ist für den Einsatz bei Patienten mit zerebral bedingten Gesichtsfelddefekten für die Selbstbeurteilung der visuellen Beeinträchtigung (vQoL) geeignet. Die Messung unspezifischer hQoL ist nicht ausreichend, um die Probleme dieser Patientengruppe widerzuspiegeln.SummaryBackgroundIn patients with visual field defects, measurement of health-related quality of life (hQoL) and vision-related quality of life (vQoL) is an important adjunct to clinical measures such as perimetry. The purpose of this study was to describe hQoL and vQoL of patients with visual field defects after cerebral lesions such as infarction, traumatic brain injury, and tumor.MethodsThe National Eye Institute – Visual Function Questionnaire (NEI-VFQ) for vQoL and the SF-36 Health Survey for hQoL were administered to 24 patients about 2 years after occurrence of the visual field defect. Visual fields were measured by standard perimetry and a near-threshold campimetric method. Visual acuity was measured by the Landolt-Ring-Test.ResultsThe NEI-VFQ scores – but not SF-36 scores – were not only lower than those of a disease-free group but also lower than those of patients with visual impairments not caused by cerebral damage. Rank correlations between the size of the visual field defect and NEI-VFQ subscales were significantly high or modest. With SF-36 scores these correlations were generally low and moderate at best.ConclusionThe NEI-VFQ is a valuable measure of self-reported visual impairment in patients with visual field defects after cerebral lesions. The measurement of unspecific hQoL is not sufficient to reflect the problems of patients with visual field defects.