To provide a systematic overview of interventions for stroke related visual impairments.
Hemianopia, partial loss of the field of vision, is a condition usually the result of a stroke although other neurological disorders such as tumours can be responsible.
From the Greek; hemi – half, an – without, opia – sight.
Damage to an individual’s brain in the area responsible for interpreting visual input is the most common cause;
Normal field of vision
The thing about hemianopia is that often the person experiencing the condition is unaware. Imagine the entire right side of your world stops existing; your brain, just as with your physiological blind-spot very quickly recovers and compensates.
People who have experienced strokes will not uncommonly eat a meal and leave half the plate, not because they can’t see it (which they can’t), but because for that person there is no right or left side of the plate.
We call this situation neglect. I guess that is apposite.
I first encountered this in Oliver Sack’s case histories. I can remember the story of a man waking-up in bed to find a strange object beside him; inert, disconnected – it was his own leg. (This might have been Alien Hand Syndrome, that is for another day.)
(For this reason, medical students, if you ever talk with someone who has experienced a major stroke, always make sure you are in their field of vision and not presenting as a disembodied voice.)
Once understanding this concept, I thought I would stretch the idea to include the way that certain branches of management operate.
It is all too easy for me to pick hospital management, but, what the heck.
Imagine you are running an organisation – it is perhaps doing OK, books balanced, care, treatment, production all at levels you anticipated at the start of the year; the plan is on plan. Beautiful; you can even go on holiday and chill-out.
If back home things go wrong; I don’t know, perhaps, the money that was thought to be in the bank is actually a deficit or, the equipment you have been using to undertake operations is in some way faulty, you have two options.
One, investigate, get as much information as possible, conclude and communicate.
The other, is to do the above, but pretend all is OK; assume that everything will be well – this, the ostrich strategy you might call it is more common within organisations than at first might seem logical; we have the 2007/8 Global Financial Crisis as a case study.
Much analysis has happened since that time and is ongoing; in healthcare, our equivalent is the Mid Staffordshire Hospitals – is disaster the wrong word*? People running so fast on a treadmill that if they get off the uncertainty is more frightening than their high-speed collapse.
Good, clever, insightful people become blinded to what is obvious; hemianopia. It is there, it is clear to everyone else, but in the case of the afflicted it doesn’t exist.
Other words are lacuna, scotoma, absence.
Through careful therapy, a person can recover from hemianopia – utilising mirror-neurones, physical and psychological treatments, that which was lost can return.
How do we support those caught in management hemianopia to recover? Is there a treatment or a means of defence?
Be open, honest, vulnerable and candid.
Don’t hide behind false prophets or slogans.
Acknowledge that the world is never entirely knowable; accept dissonance. Ask for help.
And, if the humility isn’t there? If the situation is extreme and the walls falling-down?
What would you do?
*Officially it was a ‘scandal’
Hemianopia, also referred to as hemianopsia, comes from a culmination of three different Greek words: “hemi” translates to “half,” “an” translates to “without,” and “opsia” translates to “vision.” Hence, it literally means “being without half of your vision.”
This is a condition where half of your visual field can either be completely blind or partially diminished as a result of head trauma, a tumor, or suffering a stroke.
People who suffer from migraine headaches may sometimes experience temporary hemianopia or other visual disturbances, but this typically subsides on its own after a migraine goes away.
Homonymous hemianopia occurs when you lose part of your visual field on the same side of both eyes. This happens frequently to stroke patients or people who’ve suffered traumatic brain injuries. Visual images that are captured on the left side of the brain are communicated to the right side and vice versa, which is why hemianopia typically affects the same side of each eye equally.
The opposing posterior sides of the brain correspond to the opposite eye, which means that if an injury occurs on the left side of the brain, the visual field defects occur in the right eye.
As an umbrella medical term, there are actually five types of hemianopia and two subcategories in total. In fact, the hemianopia type that a patient suffers from is typically correlated with the exact site of the visual field defect.
Visual field is lost on the same side in both eyes, depending on which side of the brain is affected by a stroke or injury. The left optic nerve controls the right visual field and the right optic nerve controls the left visual field. The diminished vision is instrumental in helping doctors locate the exact area of the brain that’s been injured or where the stroke occurred.
Loss of vision occurs in different fields of the eyes. Heteronymous hemianopia is separated into two different categories:
Binasal hemianopia: Blindness or vision loss occurs in the field of vision that’s within the closest proximity to the nose. This is caused by lateral damage to the retinal nerve fibers that don’t cross in the optic chiasm. They’re also responsible for registering information and sending it to the temporal retina.
Bitemporal hemianopia: As the name suggests, bitemporal hemianopia is a loss of vision that happens on the side of the eyes that’s closest to the temple. Lesions and damage to the optic chiasm can cause bitemporal hemianopia. The optic chiasm is located near the pituitary gland where the nerves from the left and right eyeballs meet and cross over one another to reach the opposite side of the brain.
Loss of vision occurs in one quadrant or portion of the visual field, and this usually depends on the part of the brain that’s damaged. The area that’s connected to the damaged portion of the brain will suffer either partial or complete hemianopia.
Superior hemianopia:Superior hemianopia is when loss of vision occurs in the upper visual field of either the left or right eye or both.
Inferior hemianopia:Inferior hemianopia is when loss of vision occurs in the lower visual field of either the left, right, or both eyes.
There are several different factors or injuries that can cause hemianopia including brain injuries, strokes that occur in certain parts of the brain, and physical head trauma.
As mentioned, while severe migraines can cause temporary hemianopia and adversely affect the patient’s vision, this symptom typically subsides on its own once the migraine pain is relieved.
However, there are more permanent and hazardous causes of permanent hemianopia.
Damage to certain parts of the brain such as blunt force trauma due to an accident or sports injuries accumulated over an extended period of time can lead to hemianopia in the visual fields of the eyes. These injuries can incur the growth of lesions or contusions on the brain over long periods of time, which can cause hemianopia in old age or even earlier on in life depending on the severity and frequency of the injuries.
As brain tumors begin to form and continue to grow over time, they can have the same effects as traumatic brain injuries. Eventually, the pressure and damage caused by the tumor can directly result in hemianopia in either one or both of the eyes.
Strokes typically occur as a result of insufficient supply of oxygen reaching the brain. Oxygen is important because it promotes healthy and stable cranial functions. The blockages happen for a number of reasons, the most common one being the formation of blood clots. Depending on the severity of the stroke, it could be fatal for the person who endures it. While survival is certainly preferable, it also means enduring various physical and mental ailments, including hemianopia.
Hemianopia has a variety of signs and symptoms that are associated with it, including the following:
In addition to the physical indicators of hemianopia, there are also a few psychological, emotional, cognitive, and even social repercussions. Many patients who suffer from hemianopia can become increasingly frustrated or frightened as their condition worsens because it can make mobility and attending social events extremely difficult. As a result, this loss of field vision can also have a negative effect on a person’s ability to live independently and a lot of patients may become gradually reclusive because they fear the outside world and enduring potential injuries.
Mounting irritation, aggravation, and stress also accompany hemianopia because people who suffer from it constantly think that people are bumping into them or objects are appearing out of nowhere. This can make it virtually impossible to function normally in crowded places. Part of the problem is that a lot of people don’t even realize that they have hemianopia until they’re officially diagnosed with it.
In order to accurately diagnose hemianopia, your optometrist will most likely send you to a specialist who will then conduct a series of tests on your vision. They’ll start off by asking you a series of questions with the intent of gaining a thorough and clear understanding of the symptoms you’re experiencing. You’ll also undergo a series of visual tests using a machine called a Humphrey Field Analyzer.
This machine tests the depth of vision in each eye individually. It flashes lights in each possible point of your vision including the upper left, lower left, upper right, lower right, and the center. All you have to do is press a button to indicate when you see the light. If the machine detects that you’ve missed the light multiple times in the same areas, it’ll determine that there may be blank patches within your visual field and this is an indication that you may have hemianopia.
Following this assessment, if it’s determined that you do have hemianopia, your doctor may then order a series of MRI tests to establish the initial cause of this condition, whether it was a brain injury, stroke, or a tumor.
It’s important to note that while hemianopia treatments can be highly effective and rehabilitative, there’s no actual cure for this condition and you will have to continuously undergo various relief methods that can only stand to improve the condition and make it more manageable.
That said, the following is a list of treatment options for hemianopia. It’s up to your doctor to determine which one would be the most suitable for you depending on the type and severity of the hemianopia you have. In some cases, it might even be appropriate and useful to incorporate a combination of these treatments. Again, your doctor will typically use their own expertise and discretion in such cases.
This is provided by NovaVision and uses computerized software to help improve patients’ vision in half-hour increments where the patient is instructed to focus their gazes on a specified point and must move their head whenever they see a flash of light or other stimuli in their field of vision. This information is recorded by the computer and the treatment is adjusted with each session and progress of the patient.
This is a multi-sensory visual training approach to attempting to improve the visual fields of people who suffer from hemianopia and it’s especially effective for treating homonymous hemianopia. It stimulates both the auditory and visual senses in an attempt to get them to work harmoniously with one another and improve the patient’s quality of life despite having this condition.
These are specialized sunglasses that are formulated specifically for each individual patient and their level of hemianopia. The sunglasses have prisms embedded in their lenses that can help enhance the patient’s vision and expand their field of vision while wearing them.
Also referred to as scanning therapy, this technique tests the speed and correlation with which both eyes move from one focal point to another. The optometrist will observe as the patient’s eyes jet from one vertical or horizontal focal point to another and examine whether the eyes separate or move in unison. People who suffer from hemianopia are taught to incorporate this visual technique in their everyday lives to help them naturally expand their field of vision in every direction.
Hemianopia can have a detrimental effect on a person’s everyday life if left untreated. Especially as people get older, they tend to become more reclusive due to this condition because they feel like burdens to their loved ones and everyone around them. People with diminished eyesight may have a hard time moving around without bumping into people or objects and because their line of vision is diminished as well, they most likely will have to surrender their driving privileges as well. This can make them feel like an even greater burden on their family and friends if they need to be driven everywhere or require the special assistance of a loved one or caregiver.
Hemianopia will undoubtedly have a strong impact on your everyday life, but that doesn’t mean it has to hold you back from being able to resume your regular activities or from doing the things you enjoy. By learning proper management and adaptation techniques, you can learn to live with and even conquer symptoms associated with hemianopia. If you’ve recently suffered a stroke, brain injury, or tumor and are noticing a vast decline in your vision, express these concerns to your doctor immediately so that they can start taking steps to administer a helpful treatment plan.
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.
“When individuals experience hemianopsia much more than just their side vision is reduced,” says Richard 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.
For more information, contact:
Tracy LeRoux, The Link Agency, Inc.
SOURCE International Academy of Low Vision Specialists
See the original video here: http://www.showme.com/sh/?h=xyvD3Gi Created by Dale Ledford, a college Biology, Human Anatomy, and Physiology instructor in Blountville, Tennessee.
The purpose of this education is to help you understand how to screen, refer and treat patients related to functional performance.
WE DO NOT DIAGNOSE!
Objectives for Today
■ Identify signs and symptoms that indicate a potential vision problem.
■ Identify the differences amongst the variety of vision problems that can occur
following a neurological event and how it impacts functional performance with
■ Identify how to accurately screen for potential vision problems and when to refer to
an eye specialist.
■ Identify therapeutic approaches used to treat and compensate for problems,
allowing for improved function.
[Purpose] Homonymous hemianopia is one of the most common symptoms following neurologic damage leading to impairments of functional abilities and activities of daily living. There are two main types of restorative
rehabilitation in hemianopia: “border training” which involves exercising vision at the edge of the damaged visual field, and “blindsight training,” which is based on exercising the unconscious perceptual functions deep
inside the blind hemifield. Only border effects have been shown to be facilitated by transcranial direct current stimulation (tDCS). This pilot study represents the first attempt to associate the modulatory effects of tDCS over
the parieto-occipital cortex to blindsight treatment in the rehabilitation of the homonymous hemianopia.
[Subjects and Methods] Patients TA and MR both had chronic hemianopia. TA underwent blindsight treatment which was combined with tDCS followed by blindsight training alone. MR underwent the two training rounds in reverse order.
[Results] The patients showed better scores in clinical-instrumental, functional, and ecological assessments after tDCS combined with blindsight rehabilitation rather than rehabilitation alone. [Conclusion] In this two-case report parietal-occipital tDCS modulate the effects induced by blindsight treatment on hemianopia.
[Conclusion] In this two-case report parietal-occipital tDCS modulate the effects induced by blindsight treatment on hemianopia.
To provide a systematic overview of interventions for stroke related visual impairments.
A systematic review of the literature was conducted including randomized controlled trials, controlled trials, cohort studies, observational studies, systematic reviews, and retrospective medical note reviews. All languages were included and translation obtained. This review covers adult participants (aged 18 years or over) diagnosed with a visual impairment as a direct cause of a stroke. Studies which included mixed populations were included if over 50% of the participants had a diagnosis of stroke and were discussed separately. We searched scholarly online resources and hand searched articles and registers of published, unpublished, and ongoing trials. Search terms included a variety of MESH terms and alternatives in relation to stroke and visual conditions. Article selection was performed by two authors independently. Data were extracted by one author and verified by a second. The quality of the evidence and risk of bias was assessed using appropriate tools dependant on the type of article.
Forty-nine articles (4142 subjects) were included in the review, including an overview of four Cochrane systematic reviews. Interventions appraised included those for visual field loss, ocular motility deficits, reduced central vision, and visual perceptual deficits.
Further high quality randomized controlled trials are required to determine the effectiveness of interventions for treating post-stroke visual impairments. For interventions which are used in practice but do not yet have an evidence base in the literature, it is imperative that these treatments be addressed and evaluated in future studies.
Visual impairments following stroke may include abnormalities of central and/or peripheral vision, eye movements and a variety of visual perception problems such as inattention and agnosia. The visual problems (types of visual impairment) can be complex including ocular as well as cortical damage (Jones & Shinton, 2006; Rowe et al., 2009a). Visual impairments can have wide reaching implications on daily living, independence, and quality of life. Links with depression have also been documented in the literature (Granger, Cotter, Hamilton, & Fiedler, 1993; Nelles et al., 2001; Ramrattan et al., 2001; Tsai et al., 2003; West et al., 2002). The estimation of the overall prevalence of visual impairment is approximately 60% at the acute stage following stroke (Ali et al., 2013; Barrett et al., 2007; Clisby, 1995; Freeman & Rudge, 1987; Isaeff, Wallar, & Duncan, 1974; Rowe et al., 2009b; Rowe et al., 2013). A review of the individual prevalence figures and the recovery rates for each of the possible post-stroke visual impairments has been reported elsewhere in the literature (Hepworth et al., 2016).
In order to treat and manage visual impairments caused by stroke it is important to establish the range and effectiveness of the available treatment options. The aim of this literature review is to provide a comprehensive synthesis of the evidence relating to treatment of visual problems after stroke.
Patients with peripheral field loss complain of colliding with other pedestrians in open-space environments such as shopping malls. Field expansion devices (e.g., prisms) can create artificial peripheral islands of vision. We investigated the visual angle at which these islands can be most effective for avoiding pedestrian collisions, by modeling the collision risk density as a function of bearing angle of pedestrians relative to the patient. Pedestrians at all possible locations were assumed to be moving in all directions with equal probability within a reasonable range of walking speeds. The risk density was found to be highly anisotropic. It peaked at ’458 eccentricity. Increasing pedestrian speed range shifted the risk to higher eccentricities. The risk density is independent of time to collision. The model results were compared to the binocular residual peripheral island locations of 42 patients with forms of retinitis pigmentosa. The natural residual island prevalence also peaked nasally at about 458 but temporally at about 758. This asymmetry resulted in a complementary coverage of the binocular field of view. Natural residual binocular island eccentricities seem well matched to the collision-risk density function, optimizing detection of other walking pedestrians (nasally) and of faster hazards (temporally). Field expansion prism devices will be most effective if they can create artificial peripheral islands at about 458 eccentricities. The collision risk and residual island findings raise interesting questions about normal visual development.
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.
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
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.
There are four ways in which vision can be affected following a stroke:
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
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:
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