Posts Tagged visual field

[Abstract+References] Combined Transcranial Direct Current Stimulation and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study

Abstract

Background

Visual field defects after posterior cerebral artery stroke can be improved by vision restoration training (VRT), but when combined with transcranial direct current stimulation (tDCS), which alters brain excitability, vision recovery can be potentiated in the chronic stage. To date, the combination of VRT and tDCS has not been evaluated in postacute stroke rehabilitation.

Objectives

To determine whether combined tDCS and VRT can be effectively implemented in the early recovery phase following stroke, and to explore the feasibility, safety and efficacy of an early intervention.

Design

Open-label pilot study including a case series of 7 tDCS/VRT versus a convenience sample of 7 control patients (ClinicalTrials.gov ID: NCT02935413).

Setting

Rehabilitation center.

Subjects

Patients with homonymous visual field defects following a posterior cerebral artery stroke.

Methods

Seven homonymous hemianopia patients were prospectively treated with 10 sessions of combined tDCS (2.mA, 10 daily sessions of 20 minutes) and VRT at 66 (±50) days on average poststroke. Visual field recovery was compared with the retrospective data of 7 controls, whose defect sizes and age of lesions were matched to those of the experimental subjects and who had received standard rehabilitation with compensatory eye movement and exploration training.

Results

All 7 patients in the treatment group completed the treatment protocol. The safety and acceptance were excellent, and patients reported occasional skin itching beneath the electrodes as the only minor side effect. Irrespective of their treatment, both groups (treatment and control) showed improved visual fields as documented by an increased mean sensitivity threshold in decibels in standard static perimetry. Recovery was significantly greater (P < .05) in the tDCS/VRT patients (36.73% ± 37.0%) than in the controls (10.74% ± 8.86%).

Conclusion

In this open-label pilot study, tDCS/VRT in subacute stroke was demonstrated to be safe, with excellent applicability and acceptance of the treatment. Preliminary effectiveness calculations show that tDCS/VRT may be superior to standard vision training procedures. A confirmatory, larger-sample, controlled, randomized, and double-blind trial is now underway to compare real-tDCS− versus sham-tDCS−supported visual field training in the early vision rehabilitation phase.

References

  1. Roux, F. Perimetric visual field and functional MRI correlation: Implications for image-guided surgery in occipital brain tumours. J Neurol Neurosurg Psychiatry. 2001;71:505–514.
  2. Gray, C., French, J., Bates, D., Cartlidgen, Venables, G., James, O. Recovery of visual fields in acute stroke: Homonymous hemianopia associated with adverse prognosis. Age Ageing. 1989;18:419–421.
  3. Zhang, X., Kedar, S., Lynn, M., Newman, N., Biousse, V. Natural history of homonymous hemianopia. Neurology. 2006;66:901–905.
  4. Romano, J. Progress in rehabilitation of hemianopic visual field defects. Cerebrovasc Dis. 2009;27:187–190.
  5. Pöppel, E., Held, R., Frost, D. Residual visual function after brain wounds involving the central visual pathways in man. Nature. 1973;243:295–296.
  6. Weiskrantz, L., Warrington, E., Sanders, M., Marshall, J. Visual capacity in the hemianopic field following a restricted occipital ablation. Brain. 1974;97:709–728.
  7. Wüst, S., Kasten, E., Sabel, B. Blindsight after optic nerve injury indicates functionality of spared fibers. J Cogn Neurosci. 2002;14:243–253.
  8. Sabel, B.A., Fedorov, A., Naue, N., Borrmann, A., Herrmann, C., Gall, C. Non-invasive alternating current stimulation improves vision in optic neuropathy. Restor Neurol Neurosci. 2011;29:493–505.
  9. Sabel, B.A., Henrich-Noack, P., Fedorov, A., Gall, C. Vision restoration after brain and retina damage: The “residual vision activation theory”. Prog Brain Res. 2011;192:199–262.
  10. Bola, M., Gall, C., Sabel, B.A. “Sightblind”: Perceptual deficits in the “intact” visual field.Front Neurol. 2013;4:80.
  11. Bola, M., Gall, C., Moewes, C., Fedorov, A., Hinrichs, H., Sabel, B.A. Brain functional connectivity network breakdown and restoration in blindness. Neurology. 2014;83:542–551.
  12. Bola, M., Sabel, B.A. Dynamic reorganization of brain functional networks during cognition.NeuroImage. 2015;114:398–413.
  13. Bridge, H., Thomas, O., Jbabdi, S., Cowey, A. Changes in connectivity after visual cortical brain damage underlie altered visual function. Brain. 2008;131:1433–1444.
  14. Kasten, E., Wüst, S., Behrens-Baumann, W., Sabel, B.A. Computer-based training for the treatment of partial blindness. Nature Med. 1998;4:1083–1087.
  15. Gall, C., Antal, A., Sabel, B.A. Non-invasive electrical brain stimulation induces vision restoration in patients with visual pathway damage. Graefes Arch Clin Exp Ophthalmol. 2013;251:1041–1043.
  16. Eysel, U.T., Schweigart, G., Mittmann, T. et al, Reorganization in the visual cortex after retinal and cortical damage. Restor Neurol Neurosci. 1999;15:153–164.
  17. Poggel, D., Kasten, E., Sabel, B.A. Attentional cueing improves vision restoration therapy in patients with visual field defects. Neurology. 2004;63:2069–2076.
  18. Kasten, E., Bunzenthal, U., Sabel, B.A. Visual field recovery after vision restoration therapy (VRT) is independent of eye movements: An eye tracker study. Behav Brain Res. 2006;175:18–26.
  19. Nitsche, M.A., Schauenburg, A., Lang, N. et al, Facilitation of implicit motor learning by weak transcranial direct current stimulation of the primary motor cortex in the human. J Cogn Neurosci. 2003;15:619–626.
  20. Nitsche, M.A., Cohen, L.G., Wassermann, E.M. et al, Transcranial direct current stimulation: State of the art 2008. Brain Stimul. 2008;1:206–223.
  21. Antal, A., Kincses, T., Nitsche, M.A., Bartfai, O., Paulus, W. Excitability changes induced in the human primary visual cortex by transcranial direct current stimulation: Direct electrophysiological evidence. Invest Ophthalmol Vis Sci. 2004;45:702.
  22. Kraft, A., Roehmel, J., Olma, M., Schmidt, S., Irlbacher, K., Brandt, S. Transcranial direct current stimulation affects visual perception measured by threshold perimetry. Exp Brain Res. 2010;207:283–290.
  23. Plow, E.B., Obretenova, S.N., Halko, M.A. et al, Combining visual rehabilitative training and noninvasive brain stimulation to enhance visual function in patients with hemianopia: A comparative case study. PM R. 2011;3:825–835.
  24. Plow, E., Obretenova, S., Fregni, F., Pascual-Leone, A., Merabet, L.B. Comparison of visual field training for hemianopia with active versus sham transcranial direct cortical stimulation.Neurorehabil Neural Repair. 2012;26:616–626.
  25. Plow, E., Obretenova, S., Jackson, M., Merabet, L.B. Temporal profile of functional visual rehabilitative outcomes modulated by transcranial direct current stimulation.Neuromodulation. 2012;15:367–373.
  26. Hummel, F., Celnik, P., Pascual-Leone, A. et al, Controversy: Noninvasive and invasive cortical stimulation show efficacy in treating stroke patients. Brain Stimul. 2008;1:370–382.
  27. Alber, R., Cardoso, A.M., Nafee, T. Effects of non-invasive brain stimulation in cerebral stroke related vision loss. Princip Pract Clin Res. 2015;1:15–20.
  28. Rossi, S., Hallett, M., Rossini, P., Pascual-Leone, A. Safety, ethical considerations, and application guidelines for the use of transcranial magnetic stimulation in clinical practice and research. Clin Neurophysiol. 2009;120:2008–2039.
  29. Anops [computer program]. Version 2.9.6. Aachen, Germany: LinguAdapt.
  30. Bowen, D.J., Kreuter, M., Spring, B. et al, How we design feasibility studies. Am J Prev Med. 2009;36:452–457.

Source: Combined Transcranial Direct Current Stimulation and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study – PM&R

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[WEB SITE] Hemianopsia and Driving: Are We Asking the Right Questions? – brainline.org

Laura K. Windsor, O.D., F.A.A.O.  and Richard L. Windsor, O.D., F.A.A.O, Hemianopsia.net

“All great truths begin as blasphemies.”
— George Bernard Shaw

To understand the issues of driving with a homonymous hemianopsia, we have to better define the question. Too often the question is presented as, “Can an individual with homonymous hemianopsia drive safely?” This is the wrong question! The question today should be “Which homonymous hemianopsia patients are safe to drive?” Many research studies have found that even without the kind of clinical patient selection criterion, adaptive devices, therapy and driver’s training that a potential hemianopsia driver should undergo, a significant portion of hemianopsia patients in these studies demonstrated that they may have potential to drive safely.

If we look at the group of all hemianopsia patients, those who are safe to drive will be a very small group. This is owing to the great variability of associated problems of cognition, visual neglect, visual perception, alertness and ability to compensate. No clinician or researcher would ever argue that all hemianopsia patients are safe to drive.

Let us look instead at a limited group of hemianopsia patients for whom the higher order deficits have been screened to rule out cognitive deficits, visual neglect, and poor processing speed. In this group visual field expanders have been prescribed where indicated and the patients trained with these devices and given scanning training. Then these patients have been screened with a behind-the-wheel driving evaluation, we would see a much smaller group. But within that group, would emerge a patients that could have the potential to return to driving.

It is less about the visual field

Another question I see that demonstrates a failure for some to understand where the problem resides is “How much visual field is required to drive safely?” As clinicians that have worked for many decades with hemianopsia patients, we have learned that the visual field defect is only a small part of the driving safety issue. It is usually about the constellation of problems from the brain injury and each individual’s ability to compensate.

While the type and size of visual fields are factors, the higher order cognitive functions are far more important to safe driving than the size of the visual field. These higher cognitive and perceptual functions determine if the patient can safely compensate. The real question should be expanded to, “On a case-by-case basis does this patient with an acquired brain injury from stroke, tumor, trauma or other cause, have the higher-level cognitive skills, compensatory skills, optical devices, experience, stamina driving skills and discipline to drive with a reduced visual field?”

All hemianopsia are not created equal!

Let us look at two patients with identical measurable visual field, both presenting with left homonymous hemianopsias. The first has an isolated stroke in the right occipital lobe no deficits other than the visual field loss. This patient has no visual neglect and no deficits in saccadic eye movements that would impair compensatory scanning and searching into the area of loss. With training and appropriate devices, this patient may have potential to return to safe driving. The second patient has an identical appearing left homonymous hemianopsia but from a stroke in a different location, the right parietal lobe. Thus this patient also has severe left visual neglect, impairments in saccadic eye movements and thus will never return to driving. If we only look at the visual field results, these patients look identical, but they are totally different cases.

If a state law looks only at the visual field loss to determine if driving is possible, they would treat both patients the same, denying them both the option of a driver’s license. While the second patient should not drive, this can needlessly devastate the first patient’s life, robbing the patient of independence, ability to get to work, and to lead an otherwise normal life.

How do we predict safety?

The other question we must ask is, “What tests and evaluations best predict safe driving and what are the potential weaknesses that must be addressed in training?” Various neuropsychological tests can give us information on who may have potential to drive safely. More research to establish which tests give us the most effective data is needed. Additionally, behind-the-wheel research studies continue to expand our information on the unique driving behaviors of the hemianopsia driver.

Driving, however, is a complex function. Prior experience, stamina, motivation, and discipline combined with visual status and mental functioning all can shape the impact on safety. After all the testing and treatments are completed to help select those who show potential to drive, a behind-the-wheel driving evaluation with a driving rehabilitator experienced with acquired brain injury and hemianopsia is needed. Only during the behind-the-wheel examination and training can the full complexity of driving be evaluated and training performed to improve specific skills like lane position, use of optical devices and mirrors.

The most important question is, “Have we learned to treat each person as a unique individual, understanding that impairment, disability and handicap are not one in the same?”

Should state laws prevent all Hemianopsia driving?

Setting an arbitrary visual field width to discriminate against all hemianopsia patients is now seen by many current researchers as a needless burden on the portion of hemianopsia patients that have the ability to return to safe driving. Below is what a number of researchers have observed:

As Dr. Eli Peli, Senior Scientist from Harvard’s Schepens Eye Research Institute stated in Driving With Confidence, A Practical Guide to Driving with Low Vision:

“It is clear that not all people with hemianopia function at the same level and many probably could not drive safely. However, a fair percentage of these patients may compensate for their visual loss to such an extent that they can drive as safely as any driver.”

In Automobile Driving Performance of Brain-Injured with Visual Field Defects , T Schulte, H Strasburger, E Muller-Oehring, E Kasten and B Sabel 1999, American Journal of Physical Medicine & Rehabilitation, researchers performed a driving simulator-based study of six hemianopsia patients and a similar size group of normally sighted. They summarized:

“Contrary to our expectations, the findings showed no reliable difference in the performance of visually impaired and the normally sighted subjects on a driving simulator. …Thus on a practical level our results indicate that the suspension of driving privileges for persons having visual field impairments may be unwarranted on the basis of visual field loss alone.”

In a study by Racette & Casson (1999), Visual field loss and driving performance: a retrospective study Abstracts of the Eighth International Conference Vision in Vehicles, they studied 13 homonymous hemianopsia patients and 7 homonymous quadranopsia patients. They determined those who were unsafe, those who need additional assessment, and those who were safe. Only 23% of the hemianopsia patients were found unsafe and none of the quadranopsia patients were deemed unsafe.

“Clearly, the evidence provided by these reports indicate that homonymous visual field defect and homonymous hemianopia by itself can not be an absolute and inevitable contra-indication for practical fitness to drive.”

A 2009 study, On-road driving performance by persons with hemianopia and quadrantanopia, Investigative Ophthalmology Vis Sci 50 (2) 2009, J. Wood, G. McGwin, J. Elgin, M. Vaphiades, R. Braswell, D. DeCarlo, L Kline, G Meek, K Searcy and C. Owsley studied 22 hemianopsia and 8 quadranopsia patients and a normal control group driving over a 14.1 mile course of city and interstate driving. Two back seat evaluators, who were masked to the status of the patient, evaluated the drivers. They found 100% of normal drivers were safe to drive and 73% of hemianopsia and 88% of quadranopsia patients were safe to drive.

The study concluded that:

“Some drivers with hemianopia or quadrantanopia are fit to drive compared with age-matched control drivers. Results call into question the fairness of governmental policies that categorically deny licensure to persons with hemianopia or quadrantanopia without the opportunity for on-road evaluation.”

Continued research is crucial to define all of the parameters of hemianoptic driving. Information from these studies helps us define the best candidate, the areas of weakness and will guide driving rehabilitation specialists in training these patients.

A study by Bower et al, from The Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts, Driving with Hemianopia, I: Detection Performance in a Driving Simulator, published November 2009 in Investigative Ophthalmology and Visual Science, tested twelve hemianopsia patients without visual neglect or cognitive loss and twelve matched normals on a simulator test over a two hour period. The hemianopsia patients were tested without visual field expanding systems and they demonstrated significantly more difficulty in detection of suddenly appearing pedestrians on their impaired side inside the simulator.

There was great variability in pedestrian detection among the small group of 12 hemianopsia patients with older driver’s demonstrating lower rates. The authors of this study warned that simulator studies may not match results in real world driving and they further suggested that this also means we must look at each driving candidate individually. They stated:

“In determining fitness to drive for people with HH, the results underscore the importance of individualized assessments including evaluations of blind-side hazard detection.”

The same scientists now plan to do similar tests with patients using visual field expanders. Our years of work would support that the visual field expanders and training can help fill in detection of pedestrians in many patients, but more research is needed.

How could states regulate hemianopsia licensing?

It is clear from the research that we cannot make generalizations about the driving safety of all hemianoptic drivers. Thus simply removing visual field requirements could lead to hemianopsia drivers being licensed who have other cognitive or perceptual problems at make them unsafe.

States that still contain absolute prohibitions against driving with homonymous hemianopsias should consider removing these, and replacing them with a process to judge each patient individually based on current science. The process should include mandatory evaluation with a low vision specialist experienced in hemianopsia for evaluation and treatment followed by additional therapy/training as needed including occupational therapy if indicated. Then a behind-the-wheel driving evaluation and training as appropriate to each case with a certified driving rehabilitation specialist should be completed.

Then, the doctor with the report of the driving rehabilitation specialist would file a special application with the state. The states medical advisory committee would review each case individually. If the application is approved, the patient would have to demonstrate adequate driving skills on an extended state behind-the-wheel test by the state driver’s license bureau. Restrictions on type of driving and time of day could be considered in each case cases.

Please contact us if you have any questions:

The Low Vision Centers of Indiana
Richard L. Windsor, O.D., F.A.A.O., D.P.N.A.P.
Craig Allen Ford, O.D., F.A.A.O.
Laura K. Windsor, O.D., F.A.A.O.
Indianapolis (317) 844-0919
Fort Wayne (260) 432-0575
Hartford City (765) 348-2020
info@eyeassociates.com

From Hemianopsia.net, The Low Vision Centers of Indiana. Used with permission. www.hemianopsia.net.

Source: Hemianopsia and Driving: Are We Asking the Right Questions?

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[Abstract] Combined tDCS and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study

Abstract

Background

Visual field defects after posterior cerebral artery stroke can be improved by vision restoration training (VRT), but when combined with transcranial direct current stimulation (tDCS) which alters brain excitability, vision recovery can be potentiated in the chronic stage. To date the combination of VRT and tDCS has not been evaluated in post-acute stroke rehabilitation.

Objective

To determine whether combined tDCS and VRT can be effectively implemented in the early recovery phase following a stroke, we wished to explore the feasibility, safety and efficacy of an early intervention.

Design

Open-label pilot study including a case series of seven tDCS/VRT versus a convenience sample of seven control patients (clinicalTrials.gov ID: NCT02935413).

Setting

Rehabilitation center

Subjects

Patients with homonymous visual field defects following a posterior cerebral artery stroke.

Methods

Seven homonymous hemianopia patients were prospectively treated with 10 sessions of combined tDCS (2mA, 10 daily sessions of 20 min) and VRT at 66 (±50) days on average post-stroke. Visual field recovery was compared with retrospective data of 7 controls, whose defect sizes and age of lesions were matched to the experimental subjects and who had received standard rehabilitation with compensatory eye movement and exploration training.

Results

All seven patients of the treatment group completed the treatment protocol. Safety and acceptance were excellent, and patients reported occasional skin itching beneath the electrodes as the only minor side effect. Irrespective of their treatment, both groups (treatment and control) showed improved visual fields as documented by an increased mean sensitivity threshold in dB (decibel) in standard static perimetry. Recovery was significantly greater (p<.05) in tDCS/VRT patients (36.73 ± 37.0%) than in controls (10.74 ± 8.86).

Conclusion

In this open-label pilot study, tDCS/VRT in sub-acute stroke was safe, with excellent applicability and acceptance of the treatment. Preliminary effectiveness calculations show that tDCS/VRT may be superior to standard vision training procedures. A confirmatory, larger-sample, controlled, randomized and double-blind trial is now underway to compare real- vs. sham-tDCS supported visual field training in the early vision rehabilitation phase.

This study was supported by the ERA-net neuron network “Restoration of Vision after Stroke (REVIS)”, (BMBF grant nr: 01EW1210).
clinicalTrials.gov ID: NCT02935413

Source: Combined tDCS and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study

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[ARTICLE] Use of NeuroEyeCoach™ to Improve Eye Movement Efficacy in Patients with Homonymous Visual Field Loss – Full Text

Abstract

Visual field deficits are common in patients with damaged retinogeniculostriate pathways. The patient’s eye movements are often affected leading to inefficient visual search. Systematic eye movement training also called compensatory therapy is needed to allow patients to develop effective coping strategies. There is a lack of evidence-based, clinical gold-standard registered medical device accessible to patients at home or in clinical settings and NeuroEyeCoach (NEC) is developed to address this need. In three experiments, we report on performance of patients on NEC compared to the data obtained previously on the earlier versions of the search task (); we assessed whether the self-administered computerised tasks can be used to monitor the progress () and compared the findings in a subgroup of patients to a healthy control group. Performance on cancellation tasks, simple visual search, and self-reported responses on activities of daily living was compared, before and after training. Patients performed similarly well on NEC as on previous versions of the therapy; the inbuilt functionality for pre- and postevaluation functions was sensitive to allowing assessment of improvements; and improvements in patients were significantly greater than those in a group of healthy adults. In conclusion, NeuroEyeCoach can be used as an effective rehabilitation tool to develop compensatory strategies in patients with visual field deficits after brain injury.

1. Introduction

We explore our surrounding environment by moving our eyes on average three times per second. The eye movement episodes are punctuated by brief periods (100–300 ms) of fixations. This pattern of activity ensures detailed image processing by the high density cone-receptor region of our central vision [1]. The resultant continuous perception of the stable world relies on amalgamation of lower resolution peripheral vision with high resolution central information in a spatiotopic frame of reference [2]. This dynamic process encompasses the suppression of noise or distractors and selective enhancement of target objects [3]. The selection of candidate targets for subsequent eye movements (saccades) is achieved through a combination of stimulus driven bottom-up and goal driven top-down mechanisms [4].

Visual field deficits often accompany lesions of the visual pathways which in turn disrupt the selection of targets falling within the impaired visual fields [5]. Abnormal patterns of eye movement are reported in approximately 60% of such cases [6]. One method for quantifying disturbances of visual processing is to make use of a visual search paradigm where the patient is required to report the presence or absence of a target amongst distractor items, often but not exclusively, presented on a computer screen [7]. The reaction times are then compared to those for target detection in the sighted field in the same individual or in a group of healthy individuals. The inverse of the slope for a linearly fitted plot of reaction times as a function of the number of distractor items reflects “search efficiency” [8]. In general, for healthy adults when targets and distractors are easily discriminable (pop-out search), the slope is shallow (high efficiency), but steeper slopes are expected when targets and distractors share features (complex or conjunction search).

Eye movement recordings of patients with visual field deficits following brain injury reveal a number of characteristics [9]. These include smaller saccade amplitudes, and, hence, a larger number of fixations; limited exploration of the contralesioned visual field; and more between-hemifield saccades often summarised as disorganised eye movements leading to slower reaction times for targets in contralesioned hemifields. Disturbances of eye movement dynamics are also reported in the sighted (ipsilesioned) hemifield [6, 10].

In clinical practice, the rehabilitation of patients with visual field deficits is often conducted by occupational therapists or low-vision experts. The aim of any intervention is to improve the patient’s interactions with their immediate surrounding and increasing their confidence in tasks such as shopping or commuting. The use of computerised visual search tasks as a rehabilitation tool to improve eye movements after brain injury was first reported in a group of 30 patients [11]. Patients were given systematic practice with large saccadic eye movements to search for targets presented at unpredictable positions in both the affected hemifield and the entire field of gaze. This class of treatment was later extended by use of a visual search paradigm to improve scanning strategy. Simultaneous recording of eye movements in a group of 60 patients provided further evidence for spatially disorganised pattern of eye movements in 60% of cases [6], with improved visual scanning in all 13 cases that underwent visual search training. With better use of the remaining sight as well as efficient search strategy, patients were able to compensate for their partial blindness; hence, the technique has been termed compensatory. This technique with various modifications has been used in 14 studies to date, with a total of 593 patients with homonymous visual field loss and persistent visual disabilities (see Table 1). Indeed a recent systematic review [12] has identified eye movement training as the most promising approach to visual rehabilitation in stroke patients.

Continue —> Use of NeuroEyeCoach™ to Improve Eye Movement Efficacy in Patients with Homonymous Visual Field Loss

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[Review] Visual field restorative rehabilitation after brain injury – Full Text 

Abstract

About 20%–30% of patients undergoing neurological rehabilitation report visual field defects, one of the most frequent of which is homonymous hemianopsia (loss of the same half of the visual field in both eyes). There is still no consensus as to whether homonymous hemianopsia is best treated in a restorative or compensatory manner. The aim of this review is to describe the effects of restorative rehabilitation, whose long-term efficacy is still being debated. We analyzed 56 articles describing the use of various techniques used to promote visual field recovery but concentrating on two approaches: “border training,” which involves exercising vision at the edge of the damaged visual field, and “blindsight training,” which is based on exercising unconscious perceptual functions in the mild of the blind hemifield where the scotoma is deep. Both techniques have been supported by functional imaging studies showing evidence of cortical rearrangement (plasticity) after rehabilitation. Although no formal meta-analysis was possible, the results of a semiquantitative evaluation suggested that the improvement in visual skills obtained is related to the type of training used: Border rehabilitation seems to improve the detection of visual stimuli, whereas blindsight rehabilitation seems to improve their processing. Finally, the addition of transcranial direct current stimulation seems to enhance the effects of visual field rehabilitation.

Introduction
Visual field defects
One of the most frequent symptoms of neurological damage is a lesion affecting the retrochiasmal visual pathways that leads to the loss of the left or right half of the visual field of both eyes depending on whether the lesion is on the right or left side of the brain. Long known as homonymous hemianopsia (HH), the effects may vary from complete blindness to the loss of only a part of the affected hemifield. The lesion affects the visual fibers posterior to the lateral geniculate nucleus (LGN) and may involve the occipital lobe (about 40% of cases), the parietal lobe (30%), the temporal lobe (25%), or the pathway between the optic tract and the LGN (5%; Grunda, Marsalek, & Sykorova, 2013).
The most frequent cause is stroke: It is estimated that 20–57% of stroke survivors are affected by HH (Rowe et al., 2009), but this percentage increases to 70% in the case of a stroke involving the district supplied by the posterior cerebral artery (Pambakian, Currie, & Kennard, 2005). Other possible causes are subarachnoid bleeding, intracerebral hematomas, cerebral traumas, tumors, and, much less frequently, brain surgery, demyelinating diseases, and congenital diseases (Zhang, Kedar, Lynn, Newman, & Biousse,2006b). About 20–30% of all of the patients admitted to neurorehabilitation wards have visual field defects (Kerkhoff, Münssinger, & Meier, 1994), whereas the visual acuity of patients with hemianopsia due to retrochiasmal lesions is generally not impaired (Zihl & von Cramon, 1982). Furthermore, according to Kerkhoff (1999), 70% of the subjects with HH show macular sparing; that is, they have a preserved area of central vision whose amplitude ranges from 2° to 5° (Wang, 2003).
The World Health Organization (2004) International Classification of Functioning, Disability and Health recognizes three principal types of visual deficiency: deficit (related to the organ), disability or limitation of activities (related to the person), and handicap or restricted participation (related to society). Homonymous visual field deficits usually cause the last two: the absence of or a deficiency in spatial information, reading disorders, and orientation deficits that cause affected subjects to bump into objects or have problems in finding their way, and major handicaps such as reduced participation in society, an inability to drive, a reduction in everyday activities, impaired independence, reduced social contacts, and severe reduction in the quality of life (Gall, Lucklum, Sabel, & Franke, 2009).
One of the main handicaps affecting the quality of life of hemianoptic patients is the reading impairment called hemianoptic alexia (Leff & Behrmann, 2008), but the occurrence and entity of the reading disorders due to HH depend on the side of the deficit and the presence of macular sparing (Schuett, 2009).

Continue —> Visual field restorative rehabilitation after brain injury | JOV | ARVO Journals

 

Flow chart of study selection.

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[ARTICLE] Peli prisms for hemianopia: An interdisciplinary approach to maximize successful adaptation – Full Text PDF

Introduction

Methodology Peli prisms consist of a new optic aid incorporated within the patient’s glasses that increase the visual field on the hemianopic side while maintaining unobstructed central vision. When this new technology was introduced to patients, our optometrist specialized in low vision noted difficulties concerning the adaptation to the optic aid and sought the collaboration of an orientation and mobility (O&M) specialist. An interdisciplinary protocol was then developed to improve the patient’s understanding of the optic aid and related strategies. The aim of this protocol is to maximize the patient’s potential in order to improve confidence and security during mobility.

Full Text PDF

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[VIDEO] Visual pathway and visual field defects – YouTube

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[WEB SITE] Stroke Victims Look to Innovative Glasses to Improve Side Vision

CORONA, Calif., May 3, 2016 /PRNewswire/ — In addition to being the fourth leading cause of death in the United States, strokes can lead to any number of life-changing disabilities. One of the most common side effects of the estimated 800,000 strokes that occur each year in the country is a loss of side vision (hemianopsia) of up to one-half to the right or the left. With May being both “Stroke Prevention Month,” as well as “Healthy Vision Month,” there is a new focus on the challenges patients with stroke-related hemianopsia face, as well as the hope that advanced Side Vision Awareness Glasses (SVAG) can provide.

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“When individuals experience hemianopsia much more than just their side vision is reduced,” saysRichard Shuldiner, OD, founder of The International Academy of Low Vision Specialists (IALVS), “Their quality of life diminishes, too.”  So concerned about bumping into others or accidentally walking off a curb or into traffic, the condition can leave patients feeling insecure in unfamiliar surroundings. Some avoid going out altogether; others struggle to make it through the day. Though no treatment can actually restore the lost field of vision for these patients, Side Vision Awareness Glasses (SVAG) serve as optical field expansion devices that can increase patients’ viewing fields, improve their safety and enhance confidence.  So effective, patients with custom-made SVAG typically experience an increase of about 15 degrees in side vision awareness immediately upon putting them on. The use of SVAG may even allow some patients to resume driving.

Developed by IALVS member Dr. Errol Rummel, Director of the Neuro-optometric Rehabilitation Clinic at the Bacharach Institute for Rehabilitation in Pomona, NJ, SVAG represents an important advancement over other devices that came before them.  Crafted of lens materials known to minimize distortion, they are noticeably thinner. Also, there is no obvious line in front of the lens, no “thick button,” and no lens strip inserted through the front of the lens. The front of SVAG’s lenses is smooth and barely distinguishable from ordinary glasses.

More important than being better looking than previous devices designed to manage the condition, SVAG provides far-improved vision by offering the widest viewing area. Their vertical edge enables a person with hemianopsia to move their eyes just a few millimeters to access the SVAG area of the lens. Unlike devices that superimpose a narrow peripheral image over a person’s central vision, SVAG is easier for patients to use, as well as to learn to use. They’re also harder to break, because there is no glued seam splitting through the lens from front to back.

Patients with hemianopsia who are acutely aware of their side vision loss can often be trained to scan their eyes to compensate for their impairment, but for those who are unaware or inattentive to the condition, which doctors term “hemianopsia with neglect,” SVAG can go beyond increasing their field of vision—they can broaden their worlds.

In any case, a qualified low vision optometrist can help you determine whether Side Vision Awareness Glasses are right for you or a loved one.  All members of The International Academy of Low Vision Specialists are low vision optometrists with extensive training and experience in assisting patients suffering from stroke-related hemianopsia. To locate a member near you, simply visit their website: www.ialvs.com or call 1-888-778-2030.

Source: Stroke Victims Look to Innovative Glasses to Improve Side Vision

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[BOOK] Oxford Textbook of Cognitive Neurology and Dementia – Google Books

Source: Oxford Textbook of Cognitive Neurology and Dementia – Google Books

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[ARTICLE] A Pilot Study of Perceptual-Motor Training for Peripheral Prisms – Full Text HTML

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Abstract

Purpose: Peripheral prisms (p-prisms) shift peripheral portions of the visual field of one eye, providing visual field expansion for patients with hemianopia. However, patients rarely show adaption to the shift, incorrectly localizing objects viewed within the p-prisms. A pilot evaluation of a novel computerized perceptual-motor training program aiming to promote p-prism adaption was conducted.

Methods: Thirteen patients with hemianopia fitted with 57Δ oblique p-prisms completed the training protocol. They attended six 1-hour visits reaching and touching peripheral checkerboard stimuli presented over videos of driving scenes while fixating a central target. Performance was measured at each visit and after 3 months.

Results: There was a significant reduction in touch error (P = 0.01) for p-prism zone stimuli from pretraining median of 16.6° (IQR 12.1°–19.6°) to 2.7° ( IQR 1.0°–8.5°) at the end of training. P-prism zone reaction times did not change significantly with training (P > 0.05). P-prism zone detection improved significantly (P = 0.01) from a pretraining median 70% (IQR 50%–88%) to 95% at the end of training (IQR 73%–98%). Three months after training improvements had regressed but performance was still better than pretraining.

Conclusions: Improved pointing accuracy for stimuli detected in prism-expanded vision of patients with hemianopia wearing 57Δ oblique p-prisms is possible and training appears to further improve detection.

Translational Relevance: This is the first use of this novel software to train adaptation of visual direction in patients with hemianopia wearing peripheral prisms.

Introduction

Peripheral prism glasses (p-prisms; also known as EP-glasses or the Peli Lens) provide up to 40° of visual field expansion for patients with homonymous hemianopia (HH), measurable with standard perimetry (Fig. 1).14 The unilateral fitting allows the prism eye to have areas of the seeing hemifield substituted with the prism-shifted views while the fellow eye continues to see the portions of the field obscured by the prisms due to the optical apical scotomas,5 resulting in true field expansion under binocular viewing conditions. P-prisms have now been evaluated in four open-label clinical studies,1,68 a randomized controlled clinical trial,9 and a pilot on-road study10 with positive results suggesting improved detection of blind side obstacles when walking and driving.
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Figure 1 (a) The binocular visual field of a patient with left HH as measured by Goldmann perimetry with V4e stimulus. (b) The binocular field of the same patient wearing oblique 57Δ p-prisms. (c) The oblique design in the permanent p-prism fitted unilaterally over the left eye as for the patient in 1b.

Continue —> TVST | A Pilot Study of Perceptual-Motor Training for Peripheral Prisms

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