Iris Mueller

Vision restoration therapy after brain damage: Subjective improvements of activities of daily life and their relationship to visual field enlargements

Patients with visual field deficits following stroke or neurotrauma can use vision restoration therapy (VRT) to increase their visual field size by about 5° of visual angle.1However, little is known about whether such visual field enlargements are relevant to visually guided activities of daily life. Specifically, we wish to know (1) if VRT affects activities of daily life (ADL) measures, and (2) to what extent any subjective changes correlate with quantitative measures of visual field enlargements. A retrospective analysis was carried out with data of 69 patients that had been interviewed after 6 months of VRT. Patient testimonials were analyzed post hoc and correlated with demographic status and pre/post VRT changes as measured by perimetric testing. As previously described, VRT significantly increased detection ability and most patients (88%) reported subjective benefits in ADL. A correlation analysis of quantitative parameters of visual field enlargements with subjective patient testimonials was perfo...

Vision restoration therapy does not benefit from costimulation: A pilot study

Visual field deficits in patients have long been considered to be nontreatable, but in previous studies we have found an enlargement of the intact visual field following vision restoration therapy (VRT). In the present pilot study, we wished to determine whether a double-stimulation approach would facilitate visual field enlargements beyond those achieved by the single-stimulus paradigm used in standard VRT. This was motivated by the findings that following visual cortex injury in animals, the size of receptive fields could be enlarged by systematic costimulation, where two stimuli were used to excite visual cortex neurons (Eysel, Eyding, & Schweigart, 1998). Patients (n = 23) with stable homonymous field deficits after trauma, cerebral ischemia, or hemorrhage (lesion age > 6 months) carried out either (a) standard VRT with a single stimulation (n = 9), or vision therapy with (b) a parallel costimulation (n = 7) or (c) a moving costimulation paradigm (n = 7). Training was carried out twice daily for 30 min over a 3-month period. Before and after therapy, visual fields were tested with 30° and 90° Tübinger automatic perimetry (TAP) and with high-resolution perimetry (HRP). Eye movements were recorded with an eye tracking system. When data of all three types of visual field training were pooled, we found significant improvements of stimulus detection in HRP (4.2%) and fewer misses within the central 30° perimetrically (−3.7% right eye, OD, or −4.4% left eye, OS). However, the type of training did not make any difference such that the three training groups profited equally. A more detailed analysis of trained versus untrained visual field areas in 16 patients revealed a superiority of the trained area of only 1.1% in HRP and between 3.5% (OS) and 4.4% (OD) in TAP. Spatial attention and alertness improved significantly in all three groups and correlated significantly with visual field enlargements. While vision training had no influence on the patients testimonials concerning their visual abilities, the patients significantly improved in a practical paper-and-pencil number tracking task (Zahlen-Verbindungs Test; ZVT). Visual field enlargement does not benefit from a double-stimulation paradigm, but visual attention seems to play an important role in vision restoration. The improvements in trained as well as in untrained areas are explained by top-down attentional control mechanisms interacting with local visual cortex plasticity.

A Treatment Outcome Prediction Model of Visual Field Recovery Using Self-Organizing Maps

Brain injuries caused by stroke, trauma, or tumor often affect the visual system that leads to perceptual deficits. After intense visual stimulation of the damaged visual field or its border region, recovery may be achieved in some sectors of the visual field, but the extent of restoration is highly variable between patients and is not homogeneously distributed in the visual field. We now assess the visual field loss and its dynamics by perimetry, a standard diagnostic procedure in medicine, to measure the detectability of visual stimuli in the visual field. Subsequently, a treatment outcome prediction model (TOPM) has been developed, using features that were extracted from the baseline perimetric charts. The features in the TOPM were either empirically associated with treatment outcomes or were based on findings in the vision-restoration literature. Among other classifiers, the self-organizing map (SOM) was selected because it implicitly supports data exploration. Using a data pool of 52 patients with visual field defects, the TOPM was constructed to predict areas of improvement in the visual field topography. To evaluate the predictive validity of the TOPM, we propose a method to calculate the receiver operating characteristic graph, whereby the SOM is used in combination with a nearest neighbor classifier. We discuss issues relevant for medical TOPMs, such as appropriateness to the patient sample, clinical relevance, and incorporation of a priori knowledge.

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

PURPOSE Systematic 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. METHODS Retrospective 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. RESULTS Near-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.). CONCLUSIONS Learning 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.

Psychological distress is associated with vision-related but not with generic quality of life in patients with visual field defects after cerebral lesions.

Considerably diminished quality of life (QoL) is observed in patients with visual field defects after lesions affecting the visual pathway. But little is known to what extent vision-and health-related QoL impairments are associated with psychological distress. In 24 patients with chronic visual field defects (mean age=56.17±12.36) the National Eye Institute-visual functioning questionnaire (NEI-VFQ) for vision-related QoL, the Short Form Health Survey-36 (SF-36) for generic QoL and the revised Symptom-Checklist (SCL-90-R) were administered. Cases with clinically relevant SCL-90-R symptoms were defined. Demographic, QoL and visual field parameters were correlated with SCL-90-R scales. About 40% of the investigated patients met the criteria for the definition of psychiatric caseness. 8/12 NEI-VFQ scales correlated significantly with SCL-90-R phobic anxiety (r-range −0.41 to −0.64, P<0.05), 5/12 NEI-VFQ scales correlated with SCL-90-R interpersonal sensitivity (−0.43 to −0.50), and 3/12 with SCL-90-R depression (−0.51 to −0.57) and obsessive-compulsiveness (−0.41 to −0.43). In contrast, only 1/8 SF-36 scales correlated significantly with SCL-90-R depression, phobic anxiety and interpersonal sensitivity (−0.41 to −0.54). No substantial correlations were observed between visual field parameters and SCL-90-R scales. Significant correlations of SCL-90-R with NEI-VFQ but not with SF-36 suggest that self-rated psychological distress is the result of diminished vision-related QoL as a consequence of visual field loss. The extent of visual field loss itself did not influence the rating of psychological distress directly, since SCL-90-R symptoms were only reported when diminished vision-related QoL was present. Patients with reduced vision-related QoL due to persisting visual field defects should therefore be offered additional neuropsychological rehabilitation and supportive psychotherapeutic interventions even years after the lesion.