Archive for category Hemianopsia

[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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[ARTICLE] Visual processing speed in hemianopia patients secondary to acquired brain injury: a new assessment methodology – Full Text

Abstract

Background

There is a clinical need to identify diagnostic parameters that objectively quantify and monitor the effective visual ability of patients with homonymous visual field defects (HVFDs). Visual processing speed (VPS) is an objective measure of visual ability. It is the reaction time (RT) needed to correctly search and/or reach for a visual stimulus. VPS depends on six main brain processing systems: auditory-cognitive, attentional, working memory, visuocognitive, visuomotor, and executive. We designed a new assessment methodology capable of activating these six systems and measuring RTs to determine the VPS of patients with HVFDs.

Methods

New software was designed for assessing subject visual stimulus search and reach times (S-RT and R-RT respectively), measured in seconds. Thirty-two different everyday visual stimuli were divided in four complexity groups that were presented along 8 radial visual field positions at three different eccentricities (10o, 20o, and 30o). Thus, for each HVFD and control subject, 96 S- and R-RT measures related to VPS were registered. Three additional variables were measured to gather objective data on the validity of the test: eye-hand coordination mistakes (ehcM), eye-hand coordination accuracy (ehcA), and degrees of head movement (dHM, measured by a head-tracker system). HVFD patients and healthy controls (30 each) matched by age and gender were included. Each subject was assessed in a single visit. VPS measurements for HFVD patients and control subjects were compared for the complete test, for each stimulus complexity group, and for each eccentricity.

Results

VPS was significantly slower (p < 0.0001) in the HVFD group for the complete test, each stimulus complexity group, and each eccentricity. For the complete test, the VPS of the HVFD patients was 73.0% slower than controls. They also had 335.6% more ehcMs, 41.3% worse ehcA, and 189.0% more dHMs than the controls.

Conclusions

Measurement of VPS by this new assessment methodology could be an effective tool for objectively quantifying the visual ability of HVFD patients. Future research should evaluate the effectiveness of this novel method for measuring the impact that any specific neurovisual rehabilitation program has for these patients.

Background

Vision is the dominant sensory function in humans because visual search and reach tasks are crucial to efficient performance of the main activities of daily life [12]. The term visual processing speed (VPS), an important variable of visual sensory function, is the amount of time needed to make a correct interaction with a visual stimulus [34]. The term correct interaction is the effective realization of a complete executive action of visual search and reach [5], e.g., visualizing a glass of water placed on a table and then grasping it by precise eye-hand coordination (EHC). Accordingly, the VPS variable defines the global reaction time (RT) that is composed of two additive RT sub-variables: search reaction time (S-RT) and reach reaction time (R-RT) [6,7,8]. Furthermore, VPS is mainly interdependent on intrinsic visual cognitive processing mechanisms, the complexity of the determined stimulus to be recognized (defined principally in terms of size, contrast, semantic content, and number of traces or interior angles [910]), the number of distractor stimuli surrounding it, and the distance from the point of fixation to the particular stimulus that the person is tasked to identify (eccentricity) [411,12,13]. Thus, VPS is a quantifiable parameter that objectively reflects a subject’s global visual ability.

Recent findings in the field of visual psychophysics show that having adequate VPS is necessary and dependent upon the proper functioning of six main brain-processing systems: auditory-cognitive, attentional, working-memory, visuocognitive, visuomotor, and executive [14,15,16,17,18]. Consequently, an acquired brain injury (ABI) that affects any of these cerebral processing systems could decrease the VPS.

ABI is one of the most important and disabling public health problems of our era due to the high incidence and prevalence [19]. Following an ABI, between 30 and 85% of patients will experience some type of visual dysfunction [2021], especially homonymous visual field defects (HVFDs) secondary to lesions involving the visual afferent pathways posterior to the chiasm [22]. Eye tracking technology has shown that HVFDs prevent patients from having the appropriate control of their oculomotor systems [23,24,25,26]. This is especially apparent in the saccadic system, because it is interdependent with the covert attention mechanisms associated with peripheral vision [2728]. Thus, patients with HVFDs tend to perform search tasks using unconscious compensatory head movements [252930] and employ longer total search times, more frequent fixations, and shorter saccades than normal controls [2331,32,33,34,35,36,37]. Therefore, these patients experience a significant reduction in their quality of life and functional independence. They complain that the time they have to invest in carrying out their daily activities is much greater than before suffering from HVFDs [3338,39,40]. In this regard, in recent years the scientific community has joined efforts to develop increasingly effective neurovisual rehabilitation training programs (NVRTPs) for these patients [41]. Different forms of NVRTPs have been developed, including compensatory NVRTP (C-NVRTP), restitution NVRTP (R-NVRTP), and substitution NVRTP (S-NVRTP) [41,42,43,44].[…]

 

via Visual processing speed in hemianopia patients secondary to acquired brain injury: a new assessment methodology | SpringerLink

Fig. 2

Fig. 2 Head Tracker System incorporated in the new software to measure the number of degrees of absolute head movements (dHM) performed by the study subjects, along the coordinate axes “X” and “Y”, while they performed the test. It consisted of specific software capable of detecting human faces (a), a fluorescent light (b), and a web camera (c) that registered the specific movement of a green point placed on a human mask positioned on the back of the subject’s head and neck (d.1 and d.2). The subject had to remain seated in front of the digital resistive-touch whiteboard at a distance of 40 cm (15.7 in.) and at 70 cm (27.5 in.) from the webcam

 

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[ARTICLE] Reversing Hemianopia by Multisensory Training Under Anesthesia – Full Text

Hemianopia is characterized by blindness in one half of the visual field and is a common consequence of stroke and unilateral injury to the visual cortex. There are few effective rehabilitative strategies that can relieve it. Using the cat as an animal model of hemianopia, we found that blindness induced by lesions targeting all contiguous areas of the visual cortex could be rapidly reversed by a non-invasive, multisensory (auditory-visual) exposure procedure even while animals were anesthetized. Surprisingly few trials were required to reinstate vision in the previously blind hemisphere. That rehabilitation was possible under anesthesia indicates that the visuomotor behaviors commonly believed to be essential are not required for this recovery, nor are factors such as attention, motivation, reward, or the various other cognitive features that are generally thought to facilitate neuro-rehabilitative therapies.

Introduction

Extensive damage to the visual cortex on one side of the brain produces blindness in the opposite hemifield (hemianopia) despite the sparing of other visual centers far from the site of the physical insult (Sand et al., 2013Goodwin, 2014). Of special note is the superior colliculus (SC), a midbrain structure that plays a major role in detecting, localizing, and orienting to visual targets. Its multisensory neurons allow it to use non-visual cues to facilitate this process (Stein and Meredith, 1993), and its location in the midbrain ensures that it is not directly damaged by a hemianopia-inducing cortical insult. Yet, as shown in the cat model of hemianopia, the loss of visual responses in the multisensory layers of the SC and the total absence of visual detection and orientation responses to contralateral visual stimuli following lesions of visual cortex reveal that it too is compromised, presumably via secondary excitotoxic injuries that may alter other input structures such as the basal ganglia (Jiang et al., 20092015). Interestingly, the dysfunction of SC appeared to be limited to its visual role. Its other sensory representations and sensorimotor roles remained intact: SC-mediated auditory and tactile detection and orientation responses were readily elicited (see also Sprague and Meikle, 1965).

Previously it was shown that hemianopia could be reversed using a non-invasive multisensory training paradigm (Jiang et al., 2015). The procedure consisted of presenting cross-modal combinations of spatiotemporally congruent auditory-visual cues in the blind hemifield of alert animals engaged in a sensory localization task. Because the animals were not deafened by the cortical lesion, they readily responded to the auditory-visual stimulus complex. After only a few weeks of daily multisensory training sessions, a striking change occurred: not only could the animals now detect and localize a visual stimulus throughout the previously blind hemifield, but they could also discriminate elementary visual patterns there. Visual responses that had been lost in the multisensory layers of the ipsilesional SC also returned, and cortico-SC circuits normally engaged in multisensory integration (i.e., projections from the anterior ectosylvian sulcus, AES) were found to be crucial for the recovery. The recovery could not be induced by training with visual or auditory cues alone. In an important series of studies in human patients, Làdavas and colleagues (Bolognini et al., 2005Leo et al., 2008Passamonti et al., 2009Dundon et al., 2015a,b) used a similar training paradigm and also met with success in evoking contralesional visual responses.

It is commonly believed that the success of this rehabilitative paradigm is a retraining of the visuomotor targeting behavior itself (see, review in Dundon et al., 2015a). In this case, the key factor would be the orienting action (initially elicited by the auditory stimulus) in the presence of the visual stimulus. Also, if true, it is reasonable to hypothesize that the effectiveness of this paradigm would be facilitated by other factors such as motivation, attention, arousal, and reinforcement, as these are commonly believed to enhance most neuro-rehabilitative therapies. An alternative explanation, however, is that the paradigm operates via the brain’s inherent mechanisms for multisensory plasticity, which operate independent of these factors and can be engaged under anesthesia (Yu et al., 2013). In this case, the requirement would only be repeated, reliable exposure to the visual-auditory stimulus complex in the blinded hemifield. The present study examined this possibility directly.

Materials and Methods

Adult mongrel cats (four male, three female) were obtained from a USDA-licensed commercial animal breeding facility (Liberty Labs, Waverly, NY, USA). The experimental procedures used were in compliance with the National Institutes of Health “Guide for the Care and Use of Laboratory Animals” (8th edition, NRC 2011) and approved by the Institutional Animal Care and Use Committee at Wake Forest School of Medicine. Each animal was first screened to ensure that it was tractable and responded to visual and auditory stimuli in both hemifields. All efforts were made to minimize the number of animals used.

Visual Detection and Orientation Testing

Visual orientation capabilities were quantitatively evaluated in a semicircular perimetry arena using previously described methods (see Jiang et al., 2015, see also Figure 1A). Animals were maintained at 80%–85% of body weight and obtained most of their daily food intake during, or immediately after, each behavioral session. Each animal was first trained to fixate directly ahead at a food reward held in forceps by one experimenter and protruded through a hole in the front wall of the apparatus 58 cm ahead at the 0° fixation point. Trial initiation was always contingent upon the animal establishing fixation. Once released by the animal handler (a second experimenter), the animal was required to move directly ahead to obtain the food reward. It was then trained to respond to the test stimulus (a white ping-pong ball at the end of a stick) presented at any 15° interval from 105° left to 105° right. This required little training as animals responded to the stimulus almost reflexively. Stimuli were presented manually and introduced suddenly from behind a black curtain while the animal was fixating. Additionally, on some trials, the ball remained hidden behind the opaque curtain and was tapped on the side of the apparatus to produce an auditory stimulus. If the animal oriented to and approached any test stimulus it was rewarded there, but could also move directly ahead to obtain a similar reward at the fixation point. The animal handler did not know the location of the upcoming test stimulus. This was determined by the experimenter holding the food reward, who also ensured that the trial did not begin if the animal had broken fixation. The verbal command “Go” triggered the release of the animal. “Catch trials” in which no stimulus was presented were interleaved with test trials at different locations to encourage the animal to minimize breaks in fixation, scanning movements, and “false” responses. Generally, in a given session, each of the 15° locations was tested at least 4–5 times. With few exceptions, the total number of trials/location was at least 100. The training criterion was an average of 95% correct responses. All animals reached criterion readily, had normal visual fields, and their weekly weight records revealed stable weight profiles.

Figure 1. The testing, training, and multisensory exposure paradigms. (A) Visual and auditory detection/localization capabilities were first assessed on both sides of space using a simple behavioral task. Cats were trained to fixate forward at 0° then orient to, and directly approach, a visual or auditory stimulus at any location in space. Visual stimuli were produced by lowering a ping pong ball below an obscuring curtain, and auditory stimuli were produced by tapping the ball against the apparatus wall while still obscured by the curtain. (B) Following surgery, a rehabilitation paradigm consisted of weekly sessions in which animals were exposed to cross-modal cues while anesthetized. As shown by the schematic at the lower left, the central LED (at 0°) of the display was briefly illuminated to signal the onset of the trial. It was followed by the combined LED-broadband noise burst at 45° in the contralesional hemifield. Traces illustrate the onset and duration of the stimuli. Panel (A) adapted from Jiang et al. (2015).

Continue —->  Frontiers | Reversing Hemianopia by Multisensory Training Under Anesthesia | Frontiers in Systems Neuroscience

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[ARTICLE] Efficacy and predictors of recovery of function after eye movement training in 296 hemianopic patients – Full Text

Abstract

Compensatory approaches to rehabilitation of vision loss as a result of brain injury are aimed at improving the efficacy of eye movements, enabling patients to bring the otherwise unseen stimuli into their sighted field. Eye movement training has shown promise in a large number of studies in small clinical populations. Nevertheless, there remain two problems; standardisation and wide accessibility. NeuroEyeCoach™ (NEC) has been developed to address both. The therapy is based on the visual search approach and is adaptive to the patient’s level of disability and the task difficulty is varied systematically through a combination of set-size and target/distractor similarity. Importantly, the therapy can be accessed online or in clinical settings, to enhance accessibility. Here we have reported on the findings from the first 296 consecutive cases who have accessed and completed NEC online, the largest cohort of patients studied to date. Patients’ performance on two objective (visual search times and errors) and one subjective (self-reported disability) measures of performance were assessed before and after therapy. The findings showed that patients improved in search time, had less errors and improved disability scores in 87% (255/294), 80% (236/294) and 66% (167/254) of all cases respectively. We examined factors age, sex, side of blindness, age at the onset of brain injury, and time elapsed between the brain injury and start of therapy as predictors of both objective and subjective measures of improvements. Age was a significant predictor of improved search errors with older patients showing larger improvements. Time between brain injury and intervention negatively influenced search reaction time, however, none of the factors could predict improved subjective reports of disability.

1. Introduction

Areas of blindness in the visual field could arise as a result of lesions along the visual pathways. Stroke is the main cause of brain injury, although trauma and elective surgery may also affect the visual pathways. There is a high incidence (60%) of visual impairments in stroke survivors (Rowe, Hepworth, Hanna, & Howard, 2016), with as many as half of those have been reported to have visual field loss (Fujino et al., 1986Zhang et al., 2006a). In post chiasmatic lesions, the resultant blindness is similar in extent within the same hemifield in both eyes, hence referred to as homonymous. Homonymous hemianopia is therefore blindness covering the entire one hemifield in both eyes.

The leading causes of sight loss such as age-related macular degeneration, cataracts, diabetic retinopathy and glaucoma, characteristically affect an individual over an extended period of time typically ranging from weeks to years (Groeneveld et al., 2019Rudnicka et al., 2015). Although the blindness is debilitating, there is scope for a period of adjustments to the gradual visual impairment. Sight loss due to brain injury on the other hand is sudden and often occurs over few hours and without prior warning. Some spontaneous recovery may take place in the acute stage of injury, but the probability of recovery diminishes rapidly with time and very little recovery of sight is expected 3–6 months post injury (de Haan et al., 2014Zhang et al., 2006b).

There are three main approaches to rehabilitation of hemianopic patients, namely substitution, restitution or compensatory approaches. Substitution refers to methods where the damaged field is imaged onto a portion of the sighted field using spectacle prisms to enable patients to see the otherwise undetected objects (Bowers, Keeney, & Peli, 2008). The method can expand the field of vision, nevertheless a number of studies have shown low compliance (Bowers et al., 2008Bowers et al., 2014). This may in parts be due to the reported difficulties that patients experience with the required shifts in attention and the distraction caused by rival information in the two eyes (Raz & Levin, 2017). Also, the benefits are of course contingent upon the use of optical devices. Hence the substitution techniques have not been widely adopted in clinical practice.

Restitution techniques are aimed at improving the visual sensitivity within the field defect. Post-geniculate lesions along the optic radiation and early cortical processing may lead to lack of conscious visual experience. However, there are numerous projections of visual information to subcortical and cortical sites that by-pass the usual retino-geniculo-striate route (Cowey, 2004Sahraie and Trevethan, 2014). The premise of restitution techniques relies on the residual capabilities of the remaining pathways enhanced through perceptual learning. That is, with repeated simulation over an extended period of time, learning can take place. Thus, associating visual stimulation with residual neuronal activity (Huxlin, 2008Sahraie, 2007). The fact that neuronal activity associated with visual stimuli, confined to the blind visual fields, can influence behaviour in forced-choice paradigms and in the absence of conscious perception is well established and is termed blindsight (Weiskrantz, 1986). Whilst there is an absence of any conscious experience in type I blindsight, some rudimentary awareness may be experienced in type II blindsight, often reported as a feeling that a visual event had taken place (Weiskrantz, 1998). Conscious visual experience lies on a continuous spectrum and systematic and repeated stimulation can lead behavioural performance from no detection ability to blindsight type I, type II, and eventually conscious vision (Sahraie, Trevethan, Macleod, Weiskrantz, & Hunt, 2013). Over the past two decades, a number of restitution techniques based on systematic stimulation have been developed. These include utilising repeated stimulation of the light flux channel in Vision Restoration Therapy (Kasten and Sabel, 1995Poggel et al., 2008Romano et al., 2008). Active stimulation of motion sensitivity (Huxlin et al., 2009), spatial vision (Sahraie et al., 2006) and flicker sensitivity (Raninen, Vanni, Hyvärinen, & Näsänen, 2007) have also been used in restoration approaches. The time commitment for patients using restitution techniques is significant, often requiring adherence to the daily use of an intervention over a number of months.

Compensatory techniques rely on the patient’s intact visual field for processing the otherwise unseen stimuli, by using eye movements to bring their image onto the intact field. Although such compensatory approach is intuitive, spontaneous adaptation and development of an effective eye movement pattern is seen in only 40% of hemianopic patients (Zihl, 1995) and the majority of cases shows inefficient eye movements years after the injury. The pattern of eye movements in affected cases can be characterised as having smaller amplitude saccades, leading to requiring a larger number of eye movements to explore a given portion of the field, hence slowing down in time to explore and identify targets within the field defect (Zihl, 2011). There is also a more disorganised search strategy in that patients make more frequent between hemifield saccades. Disturbances of eye movement patterns extend to both sighted and blind hemifields (Chokron et al., 2016Zihl, 1995Zihl and Hebel, 1997). In a pioneering study (Zihl, 1988), demonstrated that hemianopic patients that undertook a visual search training (involving detection of a target item amongst distractors) had improved search times. These studies were extended by the use of computerised visual search paradigms in the same lab (Zihl, 1995Zihl, 2011) as well as others (Kerkhoff et al., 1992Mannan et al., 2010Nelles et al., 2009Nelles et al., 2001Pambakian et al., 2004Roth et al., 2009); showing an overall improvement in detection time, a reduced scanpath and a smaller number of fixations prior to target detection (for a review see Sahraie, Smania, & Zihl, 2016). It is important to note that the improvements following compensatory therapies are domain specific. For example, reading disorders are also common following stroke and online therapies such as Read-Right (Ong et al., 2012Woodhead et al., 2015) can lead to improvements in reading abilities. However, performance improvements following specific training for eye movement scanning behaviour and those for reading do not transfer (Schuett, Heywood, Kentridge, Dauner, & Zihl, 2012).

As eye movements play a crucial role in visual perception and in the interaction of an individual with their environment, it is assumed that improved eye movement efficiency could lead to a reduction in self-reported level of disability. Indeed, assessment of improvements in self-reported ratings of perceived disability, introduced by (Nelles et al., 2001) has been implemented and extended in a number of studies (Aimola et al., 2014Lane et al., 2010Mannan et al., 2010Pambakian et al., 2004). Evaluation of the functional improvement in quality of life and interaction with the environment after visual rehabilitation interventions has not been carried out in any large scale studies to date, and the reported subjective ratings in Activities of Daily Living (ADL) questionnaires remain the most widespread method for such assessments.

Recent systematic reviews of the evidence for the effects of visual rehabilitation interventions (Pollock et al., 2011Pollock et al., 2019) have suggested eye movement training to be the most promising approach to vision rehabilitation in stroke patients. There are however, two major issues that needs to be addressed if any eye movement-based intervention is to become the standard care. These include standardisation of approach and ease of access (Pollock et al., 2019). In a collaborative approach Sahraie et al. (2016) reported on development of NeuroEyeCoach™ (NEC), an eye movement intervention that was based on the original visual search task that had shown to be effective in improving search performance in hemianopia (Zihl, 1995) (also described below). NEC is a Class I CE marked medical device in the EU and is registered as an FDA 510(K) exempt medical device in the US. For the patient sample described in this paper, the cost of accessing NEC was approximately $400US. The intervention was self-administered with in-built algorithms to adapt to the patient’s level of disability and systematically train the affected individual to make effective eye movements. In addition, the intervention was deliverable over the internet, thus it could be accessed at home or in clinical settings. To further illustrate the stages involved in NEC, a demo version can be accessed here (https://novavision.com/download-neuroeyecoach-demo/).

Here, we report for the first time, on changes in performance of a large group of hemianopic patients who undertook NEC outside a clinic environment. We have obtained pre- and post-intervention self-reported assessment of ADL (referred to as disability score DS) as well as reaction time (RT) and errors (ER) on a specific search task. Improvements in RT, ER and DS have been analysed in relation to age, sex, side of blindness, age at the onset of brain injury, and time elapsed between the brain injury and start of therapy.

[…]

 

Continue —-> Efficacy and predictors of recovery of function after eye movement training in 296 hemianopic patients – ScienceDirect

Fig. 1

Fig. 1. Post- and pre-therapy average reaction times for each patient is plotted in panel (A). The dashed line denotes equal performance at both sessions and 87% of cases fall below this line, indicating faster reaction times at post-therapy. Panel (B) plots the reaction time for targets appearing on the sighted and blind field separately, again indicating that improvements take place at both sides. Error bars denote ±SEM.

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[NEWS] Ocutrx Vision Technologies promotes AR for macular degeneration

The Oculenz for macular degeneration

A California-based technology startup has developed an augmented reality headset meant to help patients cope with macular degeneration.

Mitchael Freeman, COO of Ocutrx Vision Technologies, LLC, presented the products and discussed how wearable devices, smartphones and artificial intelligence are changing healthcare at the Medical Design & Manufacturing West Conference.

Freeman highlighted the Oculenz Advanced Macular Degeneration ARwear, which has patented technology that uses complex algorithms to reposition video pixels from blurred vision areas to adjacent areas that still have viable vision.

“The speed at which wearable technology is developing and proving its utility in the healthcare space is raising a lot of eyebrows internationally,” Freeman said. “The Ocutrx technology is aimed at both improving surgery protocols and outcomes as well as assisting patients with low vision conditions such as age-related macular degeneration, amblyopia and hemianopsia. But the reality is that our tech — and other wearable tech currently in our development — can and will be used for everything from general healthcare to fitness; from remote disease monitoring to in-home pharma testing; and into advanced surgical telemedicine — and the list goes on.”

Oculenz is available for pre-order now, with shipping expected by summer.

 

via Ocutrx Vision Technologies promotes AR for macular degeneration – Products – McKnight’s Long Term Care News

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

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.

via Cognitive training in an everyday-like virtual reality enhances visual-spatial memory capacities in stroke survivors with visual field defects: Topics in Stroke Rehabilitation: Vol 0, No 0

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[VIDEO] Hemianopia conversation technique – YouTube

Left Homonymous hemianopia ways of meeting and talking to people

 

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[BLOG] My CVI Journey – A blog dedicated to sharing ideas and inspiration for helping kiddos with Cortical Visual Impairment (CVI) improve vision

 

Get Help for Cortical Visual Impairment in Ontario, Canada

Get Help for Cortical Visual Impairment in Ontario, Canada

If you reside in Ontario and you suspect your child may have Cortical Visual Impairment (CVI) or another type of visual impairment, Ontario’s Blind-Low Vision Early Intervention Program is a program that could help your family.

 

10 Toys and Other Ideas for Children with CVI

10 Toys and Other Ideas for Children with CVI

When our daughter turned 2.5 months old and still wasn’t fixing or tracking, we started to suspect she was having a problem with her vision. We knew her actual eyes were fine because she’d had eye examinations done immediately after birth, but since she’d had […]

 

 

5 Tummy Time Ideas for Babies with CVI

5 Tummy Time Ideas for Babies with CVI

For the first several months of my daughter’s life, I found getting through tummy time to be a challenge on the best of days. Most of the time, my daughter hated it. She’d cry and scream from the minute I rolled her over onto her […]

 

 

13 Ways to Build Visual Stimulation into the Daily Routine of Babies with CVI

13 Ways to Build Visual Stimulation into the Daily Routine of Babies with CVI

When I first began learning about Cortical Visual Impairment (CVI), there’s one thing that was immediately clear: it was an absolute must that my husband and I include opportunities for visual stimulation throughout our daughter’s daily routine. Our daughter’s visual therapist encouraged us to do […]

 

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