Archive for category Hemianopsia

[BLOG POST] Vision Problems Following Brain Injury | BrainLine

Tight shot of a woman's eye.

Related Content: 

What Is Hemianopsia and Why Does It Happen After TBI?

Diagnosing Vision Problems After a Brain Injury

Testing Brain Injury-Related Vision Issues with People Who Can’t Communicate

Out of all of our senses — seeing, hearing, smelling, tasting, feeling — vision is our most dominant sense. Researchers estimate that 80-85 percent of our perception, learning, and cognition are mediated through our eyes. So dealing with vision issues after a brain injury can be challenging.

Common forms of vision problems

In general, 20-40 percent of people with traumatic brain injury (TBI) experience related vision disorders. Some vision-related issues can be permanent; others resolve quickly. This depends on the individual and his unique brain injury.

Vision can be broken down into the following general categories:

  • Visual motor abilities, including alignment, refer to “eye posture” — meaning the direction in which the eyes point. For example, if the eyes are straight and aligned, the eye posture is normal.
  • Visual perception is the ability to interpret information and surroundings from visible light reaching the eye.
  • Visual acuity refers to clarity of sight.
  • Visual field is the complete central and peripheral range, or panorama of vision; picture a pie as your visual field. Here are the common types of visual field loss:
    • hemianopsia
    • quadranopsia
    • homonymous hemianopsia
    • bitemporal hemianopsia

What happens with change or loss of vision?

When we can’t see clearly or have lost part of our field of vision, everyday tasks can become more challenging, some even impossible.You might have trouble with reading, driving, dealing with bright lights, or doing activities that involve hand-eye coordination. In many cases, there are tools and strategies that can help.

Techniques and compensatory strategies

In rehab, there are various techniques and strategies to help people with vision problems after TBI. They can include:

  • Wearing prescription glasses
  • Using magnification
  • Implementing better or varying lighting for different environments
  • Using assistive technologies to help make reading and using a computer easier
  • Learning to use scanning and head turning
  • Re-teaching the eyes to move and look into missing areas in the vision field

Getting the right professional help

Someone with vision problems after a TBI should find a top-notch ophthalmologist or neurologist who can administer a comprehensive vision exam. From there, the ophthalmologist may suggest the patient work with an interdisciplinary rehabilitation team to integrate all the necessary treatments for optimal recovery.

Having vision problems after a TBI can definitely interfere with a person’s quality of life, but it doesn’t have to be that way. Vision expert Dr. Gregory Goodrich advises, “Even if your symptoms don’t seem that serious, try to find an optometrist or ophthalmologist who has experience working with people with TBI. And keep persisting until you get the help you need.”

Posted on BrainLine June 21, 2017.

Source: https://www.brainline.org/article/vision-problems-following-brain-injury?fbclid=IwAR26hKFKTmRlVm7Mkvh4eRBwLRjPZTEa0Z-nF3H7PP5cylK5FX6kdNDU4ag

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[Abstract] Using superior colliculus principles of multisensory integration to reverse hemianopia

Highlights

Unilateral blindness can be rehabilitated by multisensory training.

Training stimuli must be arranged in spatiotemporally congruent assemblies.

The training protocol is effective in human and non-human animals.

The midbrain superior colliculus is believed to support recovered vision.

Abstract

The diversity of our senses conveys many advantages; it enables them to compensate for one another when needed, and the information they provide about a common event can be integrated to facilitate its processing and, ultimately, adaptive responses. These cooperative interactions are produced by multisensory neurons. A well-studied model in this context is the multisensory neuron in the output layers of the superior colliculus (SC). These neurons integrate and amplify their cross-modal (e.g., visual-auditory) inputs, thereby enhancing the physiological salience of the initiating event and the probability that it will elicit SC-mediated detection, localization, and orientation behavior. Repeated experience with the same visual-auditory stimulus can also increase the neuron’s sensitivity to these individual inputs. This observation raised the possibility that such plasticity could be engaged to restore visual responsiveness when compromised. For example, unilateral lesions of visual cortex compromise the visual responsiveness of neurons in the multisensory output layers of the ipsilesional SC and produces profound contralesional blindness (hemianopia). The possibility that multisensory plasticity could restore the visual responses of these neurons, and reverse blindness, was tested in the cat model of hemianopia. Hemianopic subjects were repeatedly presented with spatiotemporally congruent visual-auditory stimulus pairs in the blinded hemifield on a daily or weekly basis. After several weeks of this multisensory exposure paradigm, visual responsiveness was restored in SC neurons and behavioral responses were elicited by visual stimuli in the previously blind hemifield. The constraints on the effectiveness of this procedure proved to be the same as those constraining SC multisensory plasticity: whereas repetitions of a congruent visual-auditory stimulus was highly effective, neither exposure to its individual component stimuli, nor to these stimuli in non-congruent configurations was effective. The restored visual responsiveness proved to be robust, highly competitive with that in the intact hemifield, and sufficient to support visual discrimination.

Source: https://www.sciencedirect.com/science/article/abs/pii/S0028393220300841?dgcid=rss_sd_all&utm_campaign=RESR_MRKT_Researcher_inbound&utm_medium=referral&utm_source=researcher_app

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[WEB PAGE] SeeDrivePro Visual Field Test – EyeLab – Accredited Online Sight Tests

EyeLab Visual Field Test

A simulated ‘Esterman Visual Field Test’

(EVFT) for commercial vehicle drivers

Please select one of the following two options:

First Time User Instructions Experienced EVFT User

EVFT enables drivers to test if they have the required field of vision as defined in the Regulations in the Appendix below.   This is a legal requirement for commercial vehicle drivers in the UK and many other countries.

EyeLab recommends that EVFT is checked every 12 months when taking the SeeDrivePro routine test.  This will conform to the DVLA  ‘Esterman Test’ which is described in the Regulations.

In addition to the vision test SeeDrivePro commercial vehicle drivers should have a minimum standard of visual field (peripheral vision) as tested with an Esterman Visual Field Test.

What you will need

A computer monitor or TV with a minimum horizontal width of 16 inches (41cms) or a laptop connected to the internet which has a HDMI output plus a HDMI cable to connect your laptop to the monitor.

This test should be supervised to ensure that you remain correctly positioned throughout the test.

Set-up instructions

To Continue visit Site —-> https://www.eyelab.co.uk/seedrivepro-visual-field-test/

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[VIDEO] Simple Test for Vision After Stroke (Visual Field Test) – YouTube

Famous Physical Therapists Bob Schrupp and Brad Heineck demonstrate an easy to perform visual test for someone who has had a stroke or cerebral vascular accident.

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[Abstract + References] Cognitive training in an everyday-like virtual reality enhances visual-spatial memory capacities in stroke survivors with visual field defects

ABSTRACT

Objectives

Visual field defects due to hemi- or quadrantanopia after stroke represent an under-recognized neurological symptom with inefficient instruments for neurorehabilitation to date. We here examined the effects of training in a virtual reality (VR) supermarket on cognitive functions, depressive symptoms, and subjective cognitive complaints in patients with hemianopia/quadrantanopia and healthy controls.

Methods

During a 14-day rehabilitation program, 20 patients and 20 healthy controls accomplished a real-life-like shopping task in a VR supermarket. A comparison between pre- and post-training standard neuropsychological measures, depressive symptoms, and subjective memory complaints allowed us to assess a putative transfer of rehabilitation effects from the training tasks to specific cognitive functions.

Results

The results indicate that VR training may improve performance not only in the trained task but also in specific neuropsychological functions. After the training, both patients and controls showed improved performances in visual scanning, mental rotation, visuoconstruction, and cognitive flexibility. Moreover, depressive symptoms were attenuated in both groups. In the patient group compared to the control group, the training particularly resulted in improved visual memory retrieval and reduced memory complaints.

Conclusions

The results of the current study suggest that VR training can improve particularly visual-spatial skills in patients with hemianopia or quadrantanopia. Our study thus introduces an interesting novel treatment approach to improve cognitive functions relevant to daily life in stroke patients with visual field defects

References

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Source: https://www.tandfonline.com/doi/full/10.1080/10749357.2020.1716531?scroll=top&needAccess=true

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[VIDEO] What is Hemianopsia, Causes,Types,Symptoms,Diagnosis,Treatment – YouTube

What is hemianopsia

Overview: Hemianopsia is a loss of vision in half of your visual field of one eye or both eyes. Common causes are:

  • stroke
  • brain tumor
  • trauma to the brain

Normally, the left half of your brain receives visual information from the right side of both eyes, and vice versa.

Some information from your optic nerves crosses to the other half of the brain using an X-shaped structure called the optic chiasm. When any part of this system is damaged, the result can be a partial or complete loss of vision in the visual field.

What causes hemianopsia?

Hemianopsia can occur when there’s damage to the:

  • optic nerves
  • optic chiasm
  • visual processing regions of the brain

The most common causes of brain damage that can result in hemianopsia are:

  • stroke
  • tumors
  • traumatic head injuries

Less commonly, brain damage can also be caused by:

  • aneurysm
  • infection
  • exposure to toxins
  • transient events, such as seizures or migraines

Types of hemianopsia

With hemianopsia, you can see only part of the visual field for each eye. Hemianopsia is classified by the part of your visual field that’s missing:

bitemporal: outer half of each visual field

homonymous: the same half of each visual field

right homonymous: right half of each visual field

left homonymous: left half of each visual field

superior: upper half of each visual field

inferior: lower half of each visual field

via What is Hemianopsia, Causes,Types,Symptoms,Diagnosis,Treatment – YouTube

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[WEB PAGE] WHY YOU DON’T WANT HOMONYMOUS HEMIANOPSIA AND WHAT YOU CAN DO FOR IT – Lesson

By Charles Saccarelli, ABO-AC

Release Date: June 1, 2018

Expiration Date: December 31, 2020

Learning Objectives:

Upon completion of this program, the participant should be able to:

  1. Learn how patients acquire homonymous hemianopsia.
  2. Know what vision is like for patients with homonymous hemianopsia.
  3. Understand the challenges faced by a patient with homonymous hemianopsia.

Credit Statement:

This course is approved for one (1) hour of CE credit by the American Board of Opticianry (ABO). General Knowledge Course SWJH1007


figure 1Homonymous Hemianopsia (HH) is extremely difficult to pronounce. It’s even harder to live with. And to add to the confusion, hemianopsia can also be spelled as hemianopia.

If you fancy Latin, the name tells you exactly what the condition is: Homonymous (same side) hemi (half) anopsia (blindness). So what is same side half blindness like? Many patients describe it to their doctor as having lost vision in one of their eyes. But in reality, the HH patient has a condition much more debilitating than losing vision in one eye.

A patient with a healthy visual field has about 180 degrees of horizontal visual field. Each eye has roughly 90 degrees to the temporal side toward the ear and about 60 degrees on the nasal side toward the nose. An image of a healthy visual field is shown in Fig. 1.

figure 2A patient with sight in only one eye has about 150 degrees of horizontal visual field (Fig. 2). The good eye has about 90 degrees visual field to the temporal side toward the ear and roughly 60 degrees on the nasal side toward the nose. So by losing sight in one eye, the patient is only losing 30 degrees or 17 percent of their horizontal visual field. There are other drawbacks to losing vision in one eye, but since this article is about homonymous hemianopsia, we’re not going to talk about that. We’ll stick to the visual field.

figure 3A patient with homonymous hemianopsia only has about 90 degrees of horizontal visual field. Homonymous hemianopsia can affect either side of the vision. If the patient has left homonymous hemianopsia as shown in Fig. 3, their left eye only has 60 degrees to the nasal side toward the nose, and their right eye has 90 degrees to the temporal side toward the ear. If they have right hemianopsia, their right eye only has 60 degrees to the nasal side toward the nose, and their left side has 90 degrees to the temporal side toward the ear. So by losing half their sight on the same side in each eye, they lose 90 degrees or 50 percent of their horizontal visual field. An image of a homonymous hemianopsia visual field is shown in Fig. 3.

You may be saying to yourself: “Ain’t that the darndest thing I ever did see! How does somebody get that homonyyyyy… HH?” Well, you’re reading the right article. Let’s take a quick trip back to grade school science class. The left side of the brain controls the right side of the body. The right side of the brain controls the left side of the body. Based on that logic, the right side of the brain would control the left eye, and the left side of the brain would control the right eye, right? Nope. That would have been too simple. Instead, our vision is split vertically into two hemifields, and the right side of the brain receives information from the left hemifield, and the left side of the brain receives information from the right hemifield.

We’re not going to get too crazy on anatomy, but it’s important to know what happens inside the brain that leads to a patient’s homonymous hemianopsia. The figure below shows the very basic construction of the path an image takes to reach the brain from the retina.

figure 4If trauma occurs to the optic nerve, a patient ends up blind in one eye. If trauma occurs to the optic tract, a patient ends up with homonymous hemianopsia (Fig. 4).

What can cause damage to the optic tract? A 2006 study of 904 homonymous hemianopsia patients found that 69.6 percent of HH cases were due to stroke, 13.6 percent were caused by trauma, 11.3 percent caused by a tumor, and 2.4 percent were due to surgery. On the bright side, another study showed that more than 50 percent of homonymous hemianopsia cases spontaneously resolve in the first six months, with the majority of those happening in the first month. So for many, homonymous hemianopsia is only a temporary condition. But for nearly half of the patients acquiring homonymous hemianopsia, it’s something they will have for the rest of their lives.

So now that we’ve covered what homonymous hemianopsia is like from the outside, let’s put the patient’s shoes on for a little bit, and consider what it’s like to have homonymous hemianopsia.

Are you familiar with the physiological blind spot you have in your vision—the spot where the optic nerve meets the retina? It’s a spot in your vision where you are completely blind. But you’re not consciously aware of this blind spot until you perform some sort of exercise to make you aware of it. Here’s a common exercise. Cover or close your left eye, and look at the plus sign with your right. Move your eye in, focusing on the plus sign. When your nose is somewhere between 8 and 14 inches from the plus sign, the black dot will disappear. Alternatively, you could cover or close your right eye, and look at the dot with your left, and make the plus sign disappear. It’s like magic. But it’s not magic. It’s your physiological blind spot. If you’re viewing this on a mobile device, you may need to move in even closer than 8 inches.

figure 5a & 5bThat’s kind of what it’s like to have homonymous hemianopsia, except a million times worse. Instead of a little blind spot, half of your vision is like that. Often times, field loss conditions are depicted with black. Black would be much easier for a patient to contend with, because they would be constantly aware of it. But instead of black, they see nothing in their blind field. And nothing is extremely difficult to simulate. But here’s a try. Fig. 5a shows the depiction of a left eye with a notch of blindness for the physiological blind spot. Fig. 5b shows the blind spot for homonymous hemianopsia.

VISUAL ACUITY VS. VISUAL FIELD

Our brain has a very efficient way of processing the world around us. Picture an HDTV. Every spot on the HDTV is 100 percent resolution all the time. Our eyes don’t work that way. Our eyes use maximum resolution (acuity) only in central, or foveal, vision. Our eyes then use low resolution in other areas as a cue to tell us where to look next. The chart on the left above also shows how little of our visual field is capable of maximum resolution. We only have a few degrees of vision where we’re capable of our best visual acuity. Many patients with hemianopsia have perfect visual acuity. But they are missing a substantial chunk of their visual field.

WHAT MAKES HEMIANOPSIA SO BAD?

It is often said that peripheral vision tells us where things are, and central vision tells us what things are. As you move outside of central vision, your visual acuity degrades very rapidly. Your peripheral vision provides you with spatial awareness. So when a patient acquires homonymous hemianopsia, most of what they lose is spatial awareness. They see everything on one side of their body, and nothing on the other side. It’s hard to imagine what that’s like. To simulate hemianopsia for someone curious, you can create gaze-contingent homonymous hemianopsia with some opaque tape. Bisect each pupil vertically with the tape as shown in the figure below. The reason we call this a gaze-contingent hemianopsia is it’s the only hemianopsia when you’re looking straight ahead. If you moved your eyes away from the tape, you would be able to escape the hemianopsia. If you move your eyes into the tape, you can become completely blind. Patients with real hemianopsia do not have the luxury of escaping it by looking around the tape. Walking around for a little bit with this gaze-contingent hemianopsia will give a basic idea of the impairment faced by a patient with HH.

EFFECTS OF VISUAL FIELD LOSS

When working in vision rehabilitation, practitioners often give their patients and the patient’s caregivers a quality of life survey to see what aspects of the condition are most devastating to them. This allows the practitioner to work with the patient directly on their concerns. For instance, if a patient loves playing cards, the practitioner can optimize the patient’s care plan with exercises and devices that promote playing cards. If a patient doesn’t like playing cards but loves watching TV, the practitioner would take a different approach to the patient’s care. The top three concerns of most patients with homonymous hemianopsia are driving, reading and mobility.

DRIVING

Despite driving being most patients’ number one goal, most patients with hemianopsia are unable to drive. Whether or not the patient is capable of driving, or has the potential to be a good driver with hemianopsia, state driving laws often dictate the legality of driving through visual field requirements. Here’s a story told by Mark, a hemianopsia who was still driving.

“Giving up driving was the most difficult thing that I had to deal with. I spent months and months calling doctors and different agencies. I was looking for somebody to say, ‘Yes, of course, you can drive with that vision,’ but nobody would say that. And so I went ahead and drove anyway because I had a valid driver’s license for five years. I’ll tell you exactly what happened. It was an interesting and a scary story. I’m driving a gigantic Cadillac, a ’73 Cadillac. It’s huge. And I’m driving down a hill. I have a green light so I can make a turn. But the walk sign was coming the other way. So I came down a hill, and I started to make my turn, and a college student was crossing the street… a girl… just as I made the turn, and the first time I saw her was when her head went down when the front of my car hit her. And I hit my brakes. She popped up. She was fine. And I never drove again. It was just that situation that you know… could happen. The vision was missing where I really, really needed it to see her. So anyway, that was the last time I drove.”

There are some states, such as New Jersey, with no visual field requirements to obtain a driver’s license. There are other states with very stringent field requirements, such as New York, which requires 140 degrees of visual field but does not explicitly require doctors to report visual field loss. In Pennsylvania, a doctor has an obligation to report any patient with less than 120 degrees of visual field so their license can be recalled. In California, a patient with hemianopsia must re-pass a driving test to prove they are roadworthy with their condition. Laws vary greatly state by state. But no matter what the law is, it’s important to consider the potential implications of driving with hemianopsia.

READING

In English, reading is done from left to right. Reading presents major difficulties for hemianopsia patients. Patients with left-side field loss tend to have difficulty finding the beginning of the next line of text, so they frequently get lost when transitioning from line to line. Hemianopes with right side field loss have a very difficult time because it’s hard to find the end of words, so the patient constantly finds themselves re-reading words and sentences. For instance, the word “basement” might just be read as “base” and confuse the reader, causing them to start the sentence over. Reading speed is decreased significantly for all patients with hemianopsia.

MOBILITY

Difficulties in mobility are the other commonly reported issue faced by patients with hemianopsia. The lack of awareness on the blind side can cause collisions with unexpected obstacles, but mostly causes collisions with other pedestrians. This lack of awareness is most apparent to the hemianopsia patient when they are in an environment where pedestrian traffic has no specific direction, such as a shopping mall, a grocery store or an airport terminal. To the rest of the world, hemianopsia is an invisible condition. When someone is wearing a cast or carrying a cane, the rest of the world recognizes the disability and accommodates. Because hemianopsia is not visible to the outside world, the hemianopsia patient will be viewed as clumsy, oblivious or just plain rude when they collide with pedestrians. Oftentimes this leads to a psychological discomfort in going to public places.

WHY AM I READING ABOUT THIS?

“I’m an optician! What am I going to do with this information?” There is currently no surgery or pill for helping a patient with hemianopsia. That leaves practitioners with just a couple of options—training, therapy and/or eyeglasses. Do you know anyone who knows about eyeglasses? Because they’ll be essential in fitting this hemianopsia patient with the various types of glasses available for hemianopsia.

Strokes are a very common condition, and a good optician has the potential to be a very important part of the hemianopsia patient’s care team. Your knowledge of eyeglass availability can be invaluable to the team tasked with helping the patient not only live but thrive with homonymous hemianopsia.

GLASSES FOR HEMIANOPSIA

Most of the eyeglass designs for hemianopsia are not scientifically proven to be effective. There’s a reason for this. Establishing actual scientific proof is a high bar. The gold standard for scientific proof in a medical study is a double-blind study. In a double-blind study, the practitioner doesn’t know what the patient is getting, and the patient doesn’t know what the patient is getting. This eliminates the possibility of the practitioner or patient bias entering into the study. If you’re doing a study on pills, that’s pretty easy to do. Everybody takes a white pill, and nobody knows what the white pill was until the end when the scientists are crunching the numbers to measure the results. The placebo (control) and the actual medicine (intervention) look exactly the same. When scientific studies are published, their results are published with a calculated likelihood of probability. Oftentimes, to be published, there needs to have at least a 99.5 percent chance of being accurate.

On the other end of the scientific spectrum is anecdotal evidence. The following statements are some examples of anecdotal evidence:

  • But my uncle smoked a pack of cigarettes a day and lived to be 100!
  • I rubbed liquefied eye of newt into my skin for 12 weeks, and the rash went away! That stuff is great!

If anecdotal evidence is collected from a large enough source—for instance, if you asked 10,000 people the ages of which their smoking uncles lived, it may possibly have some scientific merit. But it’s still highly prone to bias, so anecdotal evidence should be treated with caution.

My personal favorite regarding anecdotal evidence was a conversation I’ve had with multiple doctors regarding a treatment that has a highly probable scientifically proven 74 percent efficacy:

Doctor: “I tried it. It doesn’t work.”
Charlie: “Really? Our results showed about 3 in 4 success. How many patients did you try it on to determine that?”
Doctor: “One.”

I have a feeling these doctors would have scoffed at hearing the 100-year-old smoking uncle story from a patient and not even blinked at the irony.

Most glasses for hemianopsia contain prism in one form or another. It’s advisable to get a patient’s objective feedback through the use of Fresnel press-on prisms.

The lens design recommended by the doctor can be worn for a few weeks for the patient to get the feel for it, and then you can explore with the patient the possibility of getting a permanent eyeglass solution for their condition. We’ll outline the various possible lens designs a practitioner may request for homonymous hemianopsia. We’re not going to go over the potential physiological benefits and drawbacks of each lens right now. We’ll do that in a future CE.

figure 6YOKED PRISMS

Yoked prisms (Fig. 6) are the only solution in which you can possibly skip the Fresnel presson prism. In addition to the lens being more affordable than the other designs we’ll be covering, the patient has an extremely low likelihood of experiencing adverse effects from yoked prism. A yoked prism is usually prescribed with the prism base in the direction of the field loss. Optically, this strategy will shift the patient’s visual field in the direction of the field loss at all positions of gaze.

figure 7YOKED SECTOR PRISMS

Yoked sector prisms (Fig. 7) may also be called bilateral sector prisms. They are typically placed a few millimeters into the blind field. The optical effect of the lens is dependent on the patient’s position of gaze. At primary gaze, when the patient is looking straight ahead, there is no optical effect. When a patient’s gaze moves into the prisms, the visual field shifts toward the direction of the field loss.

figure 8UNILATERAL SECTOR PRISMS OR BUTTON PRISMS

Unilateral sector prisms (Fig. 8) and button prisms go by many different trademarks, but all have the same basic optical principles. At primary gaze, there is no optical effect. At a gaze into the prism, the visual field of the eye with the temporal defect’s visual field shifts in the direction of the field loss.

figure 9PERIPHERAL PRISMS

Peripheral prisms (Fig. 9) use a couple of unique optical principles called vision multiplexing and visual confusion. Rather than looking through the prisms, the patient looks between the prisms. At primary gaze, the visual field of the eye with the nasal defect has no optical effect. Images from the blind side are shifted into the seeing field on the eye with the temporal defect.

CONCLUSION

Homonymous hemianopsia is a devastating condition that affects a lot of people. The patient’s visual field is cut in half right down the middle. It affects their ability to drive, read and ambulate. Through the placement of Fresnel prisms under the direction of a doctor and through the manufacture of highly specialized lenses, an optician has the opportunity to be an important part of the hemianopsia patient’s care team. We’ll cover prism correction for this condition in more detail in a future CE course.

via Lesson: WHY YOU DON’T WANT HOMONYMOUS HEMIANOPSIA AND WHAT YOU CAN DO FOR IT

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[Abstact] Functional Connectivity of the Precuneus Reflects Effectiveness of Visual Restitution Training in Chronic Hemianopia – Full Text PDF

Abstract

Visual field defects in chronic hemianopia can improve through visual restitution training, yet not all patients benefit equally from this long and exhaustive process. Here, we asked if resting-state functional connectivity prior to visual restitution could predict training success. In two training sessions of eight weeks each, 20 patients with chronic hemianopia performed a visual discrimination task by directing spatial attention towards stimuli presented in either hemifield, while suppressing eye movements. We examined two effects: a sensitivity change in the attended (trained) minus the unattended (control) hemifield (i.e., a training-specific improvement), and an overall improvement (i.e., a total change in sensitivity after both sessions). We then identified five visual resting-state networks and evaluated their functional connectivity in relation to both training effects. We found that the functional connectivity strength between the anterior Precuneus and the Occipital Pole Network was positively related to the attention modulated (i.e., training-specific) improvement. No such relationship was found for the overall improvement or for the other visual networks of interest. Our finding suggests that the anterior Precuneus plays a role in training-induced visual field improvements. The resting-state functional connectivity between the anterior Precuneus and the Occipital Pole Network may thus serve as an imaging-based biomarker that quantifies a patient’s potential capacity to direct spatial attention. This may help to identify hemianopia patients that are most likely to benefit from visual restitution training.

via Functional Connectivity of the Precuneus Reflects Effectiveness of Visual Restitution Training in Chronic Hemianopia | bioRxiv

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[Abstract] Enhancing visual performance of hemianopia patients using overview window

Highlights

 

  • Proposal of a computational glasses for visual field defect
  • Design of a whac-a-mole task for empirical performance evaluation
  • Optimal combinations of size, position, and opacity for overlaid window

Abstract

Visual field defect (VFD) is a type of ophthalmic disease that causes the loss of part of the patient’s field of view (FoV). In this paper, we propose a method to enlarge the restricted FoV with an optical see-through head-mounted display (OST-HMD) equipped with a camera that captures an overview and overlays it on the persisting FoV. Because the overview window occludes the real background scene, it is important to create a balance between the augmented contextual information and the unscreened local information. We recruited twelve participants and conducted an experiment to seek the best size, position, and opacity for the overview window through a Whac-A-Mole task (a touchscreen game). We found that the performance was better when the overview window was of medium size (FoV of 9.148 × 5.153, nearly one third of FoV of the used OST-HMD) and placed lower in the visual field. Either too large or too small a size decreases the performance. The performance increases with increased opacity. The obtained results can legitimate the default setting for the overview window.

Graphical abstract

via Enhancing visual performance of hemianopia patients using overview window – ScienceDirect

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[WEB SITE] Homonymous hemianopia – THE BRAIN RECOVERY PROJECT

Homonymous hemianopia

Homonymous hemianopia is a  loss of half the central field as well as the entire parafoveal and peripheral field opposite the side of surgery. Homonymous hemianopia is a type of cerebral or cortical visual impairment (CVI). Cerebral/cortical vision impairment is a problem with how the brain processes what the eyes see and there are many different types of CVI.

Remember the target that is your field of vision?

Here’s how a person with right homonymous hemianopsia sees it:

Does the child see black in the lost visual field?

No. The child lacks vision in the lost visual field in the same way that you lack vision behind you. You do not see black behind you, but instead see nothing.

One way to describe this is by imagining a cape or curtain behind you which hides what you cannot see. Now pull the curtain in front of you so that it now hides everything in the lost visual field, up to half of your face. What is hidden behind the curtain is the lost visual field.

When the eyes take a picture of the object and send the message to the brain, but the message is not properly processed because of problems with the optic nerves, damage to the optic tracts or radiations, or injury to the occipital lobe, CVI is the result. In other words, there is no problem with the structure or function of the eyes, but once the visual message reaches the brain, it is lost or distorted.

Some children may have homonymous hemianopia before surgery because of the brain malformation, stroke, or disease which caused the seizures in the first place. After these surgeries, however, homonymous hemianopia is an irreversible and permanent result.

Navigating the world

Children with homonymous hemianopia often require a lot of effort to recognize that there are moving objects, people, or obstacles in their missing visual field. This makes it difficult to move from one place to another with ease, especially outdoors or in an unfamiliar environment.

For example, they may bump into pedestrians or obstacles that they simply cannot see because the object or person is in the lost field of vision. They have difficulty moving safely within their home, school, or community (known as orientation and mobility skills) and often have trouble with activities which require good vision, like team sport activities, playground games, or choosing food in a cafeteria line.

This is how persons with normal vision might view a teammate on a football field:

See how a child with left homonymous hemianopsia would miss a football player running towards him, but might still be able to catch the ball:

See how a child with right homonymous hemianopsia would see the football player, but might get hit in the face with the ball:

Some of these challenges can cause significant distress for the child which often makes them unable to fully participate in classroom and recreational activities. They may be startled when something suddenly appears in their field of vision – like a soccer ball in mid-flight – or may fear falling because they are unable to see obstacles. Although children with hemianopia may search the lost visual field by turning their head, this search may be slow.  These slow search patterns do not allow them to fully understand the environment around them fast enough to avoid an obstacle, so children with homonymous hemianopia often avoid new environments altogether.

This may also affect the child’s socio-emotional well-being. For example, the child may not be chosen for team sports during recess. Because the eyes look normal, other children and teachers may not understand how the visual field loss affects the child. They may think “they are not trying hard enough”. Homonymous hemianopia may be hidden to all.

Homonymous hemianopia can seriously affect daily activities such as walking in crowded areas such as sidewalks, shopping malls and supermarkets, classroom hallways and playgrounds, seeing playmates or teammates, identifying and finding objects, crossing the street, reading and learning, and other activities of daily living such as cooking, pouring beverages, and especially driving. Driving can be particularly dangerous – research shows that adults with homonymous hemianopsia often do not scan far enough into their lost visual field to see pedestrians or cars coming into the intersection. (This blogger shares how she came to terms with her homonymous hemianopia and decided not to drive.

These problems can lead to leaving out of important parts of a scene and, consequently, to poor comprehension and social misunderstanding.

Watch this video which simulates right homonymous hemianopia. You can see how difficult it is to view oncoming cars and pedestrians.

Reading with homonymous hemianopia

Reading requires us to move our eyes smoothly across a line of text, see each word, and understand the meaning of each word in a fraction of a second. In languages like English, Spanish, and French, the eyes must scan smoothly from left to right and top to bottom across the page, briefly fixating on a word before moving on to the next word.

Because homonymous hemianopia causes a loss of half the central field of vision, the child only sees part of the word when looking at it. This makes word identification very difficult. The child must scan to see the entire word before reading it, adding an additional step to the process of reading the word. Longer words are never seen as a whole word resulting in various reading accuracy errors. This can include misidentifying a word, omitting letters, syllables, skipping over short words unintentionally, or guessing errors.

Guessing errors can be frequent because the child does not see the entire word. The child may identify the prefix only and then fill in the rest of the word based on prior experience. (As an example, a child with left homonymous hemianopia may be attempting to read the world peach for the first time, but sees only each. They may then guess that the word being read is either each or beach depending on the context within the sentence or prior experience, rather than actually reading the entire word.)

Left-sided homonymous hemianopia, which results after right-sided surgeries, can have a significant impact on reading. Children may have problems finding the next line of text or may skip the next line altogether. Also, because the first part of a word often contains information to quickly identify it, they may have frequent reading errors. This can be especially difficult for the beginning reader.

The greatest challenge – reading with right hemianopia

Right-sided homonymous hemianopia, which results after left-sided surgeries, can have a severe impact on learning to read in children who read languages that are written and read from left to right (English, French, Spanish) as the child is always reading into the blind field.

As a reminder, skilled readers take in words from a small area around the eyes’ fixation point – about four letters to the left and 15 letters to the right. Remember this image?

The more letters you can see on the right, the faster your reading speed (known as fluency) because you know which word to focus your eyes on next. Reading after left-sided surgeries is particularly challenging because not only is most of the word missing, but the right parafoveal vision – which includes those 15 letters to right – is gone. Like this:

This loss of the right perceptual span creates a bottleneck: the child will spend too much time finding the next word, focusing on it, re-fixating on it if necessary, and then extracting its meaning. This makes oral reading performance (how fast and clearly you read out loud, known as fluency) very challenging.

Adult readers with left-sided brain injury resulting in right-sided hemianopia describe severe frustration when reading because they are attempting to read into nothingness. For a child learning to read with right homonymous hemianopia, this can cause a dislike of reading at a very early age.

What’s It’s Like To Live With Homonymous Hemianopia?

Nicola McDowell explains how she has coped with homonymous hemianopia and other cortical vision impairment throughout her life and the challenges she has experienced and overcome. She also explains her many challlenges in her terrific blog here.

Hemianopia stimulated with eye tracking software

This video first explains the various visual field deficits that can occur depending on where along the optic tract a lesion occurs. Then, starting at 3:18, this video explains hemianopsia by using eye tracking software to simulate the effects homonymous hemianosia on the screen watched by the person in the video. (In this video, hemianopsia is depicted with macular sparing – represented by the half circle in the center of the visualization. After hemispherectomy, TPO disconnection, or other surgeries which remove or disconnect the occipital lobe, mascular sparing does not occur except in rare circumstances. Instead, the blocked out area would be represented by a straight line down).

Teen With Right Hemispherectomy Reading With Eye Tracking Software

This video shows a teenager, who had right hemispherectomy as a toddler, reading with eye tracking software. Notice that he does not read lines of text smoothly, but often refixates on a word several times, skips some words, and has trouble getting to the next line of text with ease.

via Homonymous hemianopia • The Brain Recovery Project

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