Posts Tagged Hemianopia
Hemianopia leads to severe impairment of spatial orientation and mobility. In cases without macular sparing an additional reading disorder occurs. Persistent visual deficits require rehabilitation. The goal is to compensate for the deficits to regain independence and to maintain the patient’s quality of life. Spontaneous adaptive mechanisms, such as shifting the field defect towards the hemianopic side by eye movements or eccentric fixation, are beneficial, but often insufficient. They can be enhanced by training, e.g., saccadic training to utilize the full field of gaze in order to improve mobility and by special training methods to improve reading performance. At present only compensatory interventions are evidence-based.
Objectives: More than 50% of human cerebral activity is related to vision. Visual impairments are therefore common after acquired brain injury, although they are often overlooked. In order to evaluate the prevalence of visual deficits in our Out-patient Brain Injury Program, a structured screening questionnaire, the Visual Interview, was administered.
Methods: A total of 170 patients with acquired brain injury, mean age 47 years, who were enrolled in the programme during 2010–12, underwent the Visual Interview. The interview consists of 18 questions concerning visual impairment and was performed on admission. The different types of visual impairment were compared with regard to sex and diagnosis.
Results: Fifty-four percent of the patients reported visual changes, mainly reading difficulties, photosensitivity, blurred vision and disorders of the visual field. Sixteen patients who did not experience visual changes also reported visual symptoms in 4–9 questions. Only slight differences were noted in the occurrence of visual symptoms when correlated with sex or diagnosis.
Conclusion: Visual impairments are common after acquired brain injury, but some patients do not define their problems as vision-related. A structured questionnaire, covering the most common visual symptoms, is helpful for the rehabilitation team to facilitate assessment of visual changes.
The visual system is widely distributed in the brain. It is integrated in more than 50% of human cerebral activity and is fundamental for interpretation of, and interaction with, the environment (1, 2).
A pyramidal hierarchical model of visual perceptual function was presented by Warren in 1993 (3). In this model, visual cognition forms the top level, followed by, in descending order: visual memory, pattern recognition, scanning, attention and a base level holding acuity, visual fields, and ocular motor control. The model illustrates how higher visual skills evolve from integration and interaction with lower skills and how visual cognition depends on well-functioning lower levels of visual perception.
Base level disturbances, such as visual field defects (VFDs), visual acuity changes, diplopia, strabismus, photophobia and different types of binocular disorders, are common after acquired brain injury (ABI) (4, 5), and lead to chronic headache, fatigue, dizziness, reading problems, and difficulties navigating the environment (6, 7). Although a complete VFD or manifest diplopia seldom escapes notice, disturbances of ocular motor abilities and photophobia are likely to be overlooked. Examinations of convergence and accommodation are not customary in standard ophthalmological assessments. Ordinary short examinations are unable to reveal declining attention ability and fatigue. Thus, the true problems may remain hidden.
Several reports of prevalence and quality of visual deficits after ABI document visual dysfunctions in approximately 50–75% of patients (8–13). The occurrence of different visual symptoms differs between the studies, including reading disturbances, VFD, diplopia, ocular motor dysfunction and photophobia. Nevertheless, visual symptoms are often overlooked in neurorehabilitation. The observations of Sand et al. (14) are noteworthy, i.e. that 1 of 4 stroke patients with VFD, 6 months after onset of stroke, considered that their visual problems reduced quality of life and increased their disability.
Visual disturbances after ABI are common and lead to reduced quality of life. An important question is why they are so often overlooked in neurorehabilitation? A possible explanation is the difficulty for different professionals to co-operate. Vision disturbances are complex and many different professionals operate in the field. An ability to co-operate is needed for a high-quality assessment. Another explanation could be the patients’ difficulty describing their shortcomings. They experience decreased reading speed, fatigue and dizziness, but do not recognize these problems as expressions of visual deficits. A structured questionnaire at admission would help the clinician to obtain informative answers.
In 1990, Kerkhoff et al (15). compiled an “Interview Questionnaire” in order to capture visual disorders after ABI. This interview was used by Wilhelmsen 2003 (12). Jacobsson & Hamelius translated it from Norwegian to Swedish in 2010 (16). During the last 5 years we have used this questionnaire, slightly modified, termed the Vision Interview (TVI), as an aid to discover visual deficits in our Out-patient Brain Injury Program.
The aim of the present study was to examine and analyse the occurrence of self-reported visual changes in a Swedish out-patient group with medium to severe ABI, based on TVI.
Strokes, or cerebrovascular accidents (CVA) are common, particularly in older people. The problems of motor function and speech are well known. This article explains the common visual problems which can occur with a stroke and gives information about diagnosis and management.
What is a stroke?
A stroke occurs when there is an interruption to blood flow to the brain either because of a blood clot blocking the blood vessel or a haemorrhage in the brain.1 Strokes can cause signs which are obvious, such as loss of speech, drooping of one side of their face, or weakness or paralysis of the arm and/or leg on one side of the body.1 The vision is affected in about two thirds of people who have had a stroke, but this is often not obvious to the patient or their carers. For example, someone who has weakness down one side may bump into things or not eat all the food on their plate, not realising that this may also be because they have visual field loss.2
What causes a stroke?
A stroke or cerebrovascular accident, (CVA) is the result of a blocked blood vessel in the brain (thrombosis or embolus), or haemorrhage into the brain.1 Strokes are more likely in the elderly, and those who have high blood pressure, diabetes or cardiovascular disease.
Types of visual loss in people who have had a stroke
There are four ways in which vision can be affected following a stroke:
- Loss of central vision
- Visual field loss
- Visual perceptual abnormalities
- Eye movement abnormalities
These may occur in isolation but more frequently occur in combination.3 Problems with central vision are quite common after a stroke. The symptoms include blurred or altered vision. In many the vision improves, but the visual loss can be permanent.
Visual field loss occurs in up to half of people with a stroke, with the commonest defect being homonymous hemianopia in which vision is lost in the right or the left visual fields (Figure 1).4 Patients may not be aware of this, and bump into door frames or trip over things on the affected side. Reading can also be difficult (Figure 2).
Visual perceptual deficits are many and varied affecting about a third of people with a stroke. Problems that may develop include neglect one side of their body; difficulty recognising faces or objects, or difficulties with colour vision, depth perception and motion.5 Eye movement abnormalities can also be varied, including strabismus (misaligned eyes), difficulty in converging the eyes to look at near objects, or double vision due to the cranial nerves which control eye movement being affected.6 Typical symptoms include double vision, or jumbled, blurred and/or juddery vision (Figure 2).
Blurred vision, double vision and lossand loss of visual field are significant symptoms that impair daily functioning.7 The patient or their close relatives may report that they frequently bump into objects such as door frames; have difficulty finding things on surfaces; are unsure of their footing while walking and stumble; may leave food uneaten on one side of the plate and have difficulty with reading. Other impacts on the quality of life include loss of confidence, fear of falling, fear of going out alone, social isolation and loss of independence.8
How to assess visual function in someone who has had a stroke
Examination for visual loss is essential for stroke survivors.9 There are various assessment tools which can be used to examine visual function after a stroke:
- UK National Clinical Guidelines for Stroke
- UK stroke/vision resources and factsheets
- UK Stroke Association stroke/vision factsheet
- UK Royal National Institute for the Blind stroke/vision factsheet
Treatment options aim to restore visual function to as normal as possible.10 For eye movement abnormalities,prisms and patching one eye can be effective in reducing double vision.6 For visual field loss a Cochrane systematic review reports favourable evidence of visual scanning training which aims to compensate for the visual field loss.11 It is available as a paper training option (www.strokevision.org.uk) or through computer training (www.eyesearch.ucl.ac.uk; www.readright.ucl.ac.uk.
Stroke survivors with persistent impairment of central vision may be helped by low vision services which can include magnifiers, reading aids, computerised adaptations and improved lighting.12 Furthermore, simple adaptations can be made by stroke survivors such as using large print, ensuring good lighting at home, putting labels or coloured stickers on cooking equipment, decluttering areas and having a companion when going out, particularly in busy, crowded places.10
Post-stroke difficulties in visual function are an under-recognised problem that cause significant impact to the quality of life of stroke survivors. Carers and health workers need to be aware that problems with vision are a common consequence of stroke that is not outwardly obvious. Assessment including visual functioning is best provided as part of a multi-disciplinary team on acute stroke units, or in neuro-rehabilitation units. A careful history about visual problems from the patient and carers followed by examination of visual acuity, eye movements and visual field are important in understanding the difficulties in visual functioning.
Management should be tailored to each individual, their visual difficulties and visual needs. With about one quarter of stroke survivors being of working age, rehabilitation in the conext of adaptation of the work place environment is vital if younger people are to return to work after stroke. Rehabilitation requires patience and perseverance on the side of the client, relatives and the health provider.
Despite improvement in stroke prevention and acute stroke management, the increasing ageing population will result in more stroke survivors requiring rehabilitation. Policy makers need to understand the importance of providing post-stroke rehabilitation services including visual functioning.
All webpages accessed 30th January 2017
1 World Health Organization. Stroke and cerebrovascular accident. 2017. http://www.who.int/topics/cerebrovascular_accident/en/
2 Hepworth LR, Rowe FJ, Walker MF, Rockliffe J, Noonan C, Howard C, Currie J. Post-stroke Visual Impairment: A Systematic Literature Review of Types and Recovery of Visual Conditions. Ophthalmology Research: An International Journal. 2015; 5(1). ISSN: 2321-7227
3 Rowe FJ, VIS group. Visual impairment following stroke. Do stroke patients require vision assessment? Age and Ageing. 2009; 38: 188-193
4 Rowe FJ, VIS UK. A Prospective Profile of Visual Field Loss following Stroke: Prevalence, Type, Rehabilitation, and Outcome. BioMed Research International, vol. 2013, Article ID 719096, 1-12, 2013. doi:10.1155/2013/719096.
5 Rowe FJ, VIS group. Visual perceptual consequences of stroke. Strabismus 2009; 17: 24-28
6 Rowe FJ, VIS group. The profile of strabismus in stroke survivors. Eye 2010; 24: 682-5
7 Rowe FJ, VIS Group. Symptoms of stroke related visual impairment. Strabismus, 2013; 21: 150-4
8 Hepworth L, Rowe FJ. Visual impairment following stroke – the impact on quality of life: a systematic review. Ophthalmology Research: an international journal. 2016; 5(2): 1-15
9 Rowe FJ. The importance of accurate visual assessment after stroke: Editorial. Expert Reviews in Ophthalmology. 2011: 6; 133-6
10 Rowe FJ. Care provision and unmet need for post stroke visual impairment; Final report. 2013. http://www.stroke.org.uk/sites/ default/files/final_report_unmet_need_2013.pdf?
11 Pollock A, Hazelton C, Henderson CA, Angilley J, Dhillon B, Langhorne P, Livingstone K, Munro FA, Orr H, Rowe FJ, Shahani U. Interventions for visual field defects in patients with stroke. Cochrane Database of Systematic Reviews 2011, Issue 10. Art. No.: CD008388. DOI: 10.1002/14651858.CD008388.pub2.
12 Virgili G, Rubin G. Orientation and mobility training for adults with low vision. Cochrane Database of Systematic Reviews 2010, Issue 5. Art. No.: CD003925. DOI: 10.1002/14651858.CD003925.pub3
- Humphrey perimetry shows partial field recovery in patients with homonymous visual field defects after post-chiasmatic lesions.Visual decision-making is deviating from healthy controls, even in the ipsilateral, assumed ’intact’ visual field.Patients, however, do show a slight hint of primacy as healthy controls, but these effects are disrupted by their tendency to guess.Rehabilitation methods may profit from training focused on improving visual decision-making of the defective and the intact visual field.
Intense visual training can lead to partial recovery of visual field defects caused by lesions of the primary visual cortex. However, the standard visual detection and discrimination tasks, used to assess this recovery process tend to ignore the complexity of the natural visual environment, where multiple stimuli continuously interact. Visual competition is an essential component for natural search tasks and detecting unexpected events.
Our study focused on visual decision-making and to what extent the recovered visual field can compete for attention with the ’intact’ visual field. Nine patients with visual field defects who had previously received visual discrimination training, were compared to healthy age-matched controls using a saccade target-selection paradigm, in which participants actively make a saccade towards the brighter of two flashed targets. To further investigate the nature of competition (feed-forward or feedback inhibition), we presented two flashes that reversed their intensity difference during the flash. Both competition between recovered visual field and intact visual field, as well as competition within the intact visual field, were assessed.
Healthy controls showed the expected primacy effect; they preferred the initially brighter target. Surprisingly, choice behaviour, even in the patients’ supposedly ‘intact’ visual field, was significantly different from the control group for all but one. In the latter patient, competition was comparable to the controls. All other patients showed a significantly reduced preference to the brighter target, but still showed a small hint of primacy in the reversal conditions.
The present results indicate that patients and controls have similar decision-making mechanisms but patients’ choices are affected by a strong tendency to guess, even in the intact visual field. This tendency likely reveals slower integration of information, paired with a lower threshold. Current rehabilitation should therefore also include training focused on improving visual decision-making of the defective and the intact visual field.
[ARTICLE] Neuropsychologic Testing in Chiasmal Patients Exhibiting Inattention in the Temporal Visual Space during Monocular Visual Testing – Full Text PDF
Objective: By means of neuropsychologic tests, to further analyse a specific chiasmal monocular visual testing behaviour, here labelled temporal blocking because of the elective ignorance of optotypes on the temporal side of the chart. Often it is combined with impairment of reading and other cognitive impairments.
Methods: Eighteen patients with lesions to the chiasm and some degree of temporal blocking aged 24 – 76 years underwent:
- tests for visual neglect (Gothenburg test; behavioural inattention tests: star cancellation; line bisection);
- visuo-perceptual tests; and
- a test involving reading a crowded ten-letter and cipher bar.
Results: The temporal blocking in two patients recovered after emergency neurosurgery and their results were normal when subsequently tested. Of the 16 patients with deficiencies, 14 had a poorer left eye (p < 0.01).
Conclusions: The best neuropsychologic tests appeared to be those for visual neglect and the crowded bar test. In most cases, the right cerebral hemisphere’s lack of some crossed information from the left eye, usually needed for normative saccades and adjustment to visual space, may be a factor underlying the specific visual behaviour.
[WEB SITE] Global Hemianopsia Market Size, Technology, Emerging Factors, Drivers, Competitive Analysis and Forecast to 2022
Market research future published a half-cooked research report on global Hemianopsia market. The global Hemianopsia market is expected to grow with CAGR of ~6.1% during the period 2016 to 2022.
The global Hemianopsia market has been evaluated as a growing market and it is expected that the market will touch high growth figures. The rising aged population affected by Hemianopsia and increasing demand for new and improved treatment is boosting the revenues per year.
Major Key Players
- RetroSense Therapeutics, LLC
- Chadwick Optical
- Vycor Medical, Inc.,
Segmentation by Type
- Homonymous Hemianopsia
Segmentation by treatment
- Vision Restoration Therapy
- Visual Field Expander Aid
Segmentation by end user
Global Hemianopsia Market:
Hemianopsia can affect the ability to drive or read which may result in injuries due to falls or inability to navigate around obstacles. The common causes of hemianopsia include traumatic brain injury (14% of cases), tumors (11% of cases), infarction (11%–23%), and cerebral hemorrhage (7%–11%).
Taste the market data and market information presented through more than 50 market data tables and figures spread in 80 numbers of pages of the project report. Avail the in-depth table of content TOC & market synopsis on “Hemianopsia Market Research Report- Global Forecast to 2022”
Market Research Analysis:
The potential causes are dependent on the age of the patient. The most common cause in adults is stroke. Nearly, 8%–10% of stroke patients have permanent Hemianopsia and 52%–70% of hemianopsia are caused by stroke. In the coming years, it is expected that the global Hemianopsia market will advance with higher growth rate as compared to previous years. The increasing technological advancement for therapies has boosted the growth of the market.
This research report has provides the insights, on various levels of analyses such industry analysis, market share analysis leading market players and their profiles. This report also helps in studying the target segments by providing views on emerging & high-growth segments and market conclusion.
Together the market data comprise and discuss with the basic assessments on the competitive scenarios & strategies, of the global Hemianopsia market, including the high-growth regions, countries and their political, economic and technological environments. Furthermore the project report also provides the views over the historical market values as well as, pricing and cost analysis of the same.
Browse Full Report Details @ https://www.marketresearchfuture.com/reports/hemianopsia-market-research-report-global-forecast-to-2022
1.2 Scope of Study
1.3 Research Objective
1.4 Assumptions & Limitations
1.5 Market Structure
2 Research Methodology
2.1 Research Process
2.2 Primary Research
2.3 Secondary Research
3 Market Dynamics
3.5 Macroeconomic Indicators
4 Market Factor Analysis
4.1 Porter’s five forces model
4.1.1 Bargaining Power of suppliers
4.1.2 Bargaining Power of Customer
4.1.3 Intensity of Competitor’s
4.1.4 Threat of New Entrants
5 Global Hemianopsia Market, by Types
5.1.1 Homonymous Hemianopsia
6 Global HemianopsiaMarket, by Treatments
6.1.1 Vision restoration therapy
6.1.2 Visual field expander aid
7 Global Hemianopsia Market, by End users
Am J Phys Med Rehabil. 2016 Aug 22. [Epub ahead of print]
Visual impairments are common after traumatic brain injury (TBI) and negativelyaffect quality of life. We describe a 39-year-old woman with a severe TBI who wasevaluated by the inpatient optometry and vision rehabilitation service withfindings of complete right homonymous hemianopia and right cranial nerve IIIpalsy with 30-degree right exotropia (eye turn out) and complete right ptosis(eyelid will not open). The 30-degree exotropia advantageously generated 30degrees of right visual field expansion when the right ptosis was treated with amagnetic levator prosthesis, which restores eyelid opening. Once opened, thepatient used visual field expansion derived from a right exotropia to overcomefunctional impairments caused by right hemianopia. Field expansion improved thepatient’s wheelchair mobility and reaching tasks during inpatient therapy. Thisis the first report of visual field expansion by strabismus facilitated bycorrection of ptosis. Strabismus should be considered for its potential fieldexpansion benefits when homonymous visual deficits are present, beforeconsidering patching. A multidisciplinary vision rehabilitation team is wellsuited to make this determination.
[Abstract] Avoiding unseen obstacles: Subcortical vision is not sufficient to maintain normal obstacle avoidance behaviour during reaching
Previous research found that a patient with cortical blindness (homonymous hemianopia) was able to successfully avoid an obstacle placed in his blind field, despite reporting no conscious awareness of it (Striemer, C. L., Chapman, C. S., & Goodale, M. A., 2009, PNAS, 106(37), 15996-16001). This finding led to the suggestion that dorsal stream areas, that are assumed to mediate obstacle avoidance behaviour, may obtain their visual input primarily from subcortical pathways. Hence, it was suggested that normal obstacle avoidance behaviour can proceed without input from the primary visual cortex. Here we tried to replicate this finding in a group of patients (N=6) that suffered from highly circumscribed lesions in the occipital lobe (including V1) that spared the subcortical structures that have been associated with action-blindsight. We also tested if obstacle avoidance behaviour differs depending on whether obstacles are placed only in the blind field or in both the blind and intact visual field of the patients simultaneously. As expected, all patients successfully avoided obstacles placed in their intact visual field. However, none of them showed reliable avoidance behaviour – as indicated by adjustments in the hand trajectory in response to obstacle position – for obstacles placed in their blind visual field. The effects were not dependent on whether one or two obstacles were present. These findings suggest that behaviour in complex visuomotor tasks relies on visual input from occipital areas.
[ARTICLE] Peli prisms for hemianopia: An interdisciplinary approach to maximize successful adaptation – Full Text PDF
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.