Hemianopic Visual Field Loss Research Articles

Adaptation to post-stroke homonymous hemianopia – a prospective longitudinal cohort study to identify predictive factors of the adaptation process

Purpose To determine any factors that predict how an individual will adapt to post-stroke hemianopic visual field loss, with close monitoring of the adaptation process from an early stage. Materials and methods The Hemianopia Adaptation Study (HAST) is a prospective observational longitudinal cohort clinical study. Adult stroke survivors (n = 144) with new onset homonymous hemianopia were monitored using standardised mobility assessment course (MAC) as the primary outcome measure of adaptation. Results Several baseline variables were found to be good predictors of adaptation. Three variables were associated with adaptation status at 12-weeks post-stroke: inferior % visual field, % total MAC omissions, and MAC completion time (seconds). Baseline measurements of these variables can predict the adaptation at 12 weeks with moderate to high accuracy (area under ROC curve, 0.82, 95% CI 0.74–0.90). A cut-off score of ≤25% target omissions is suggested to predict which individuals are likely to adapt by 12-weeks post-stroke following gold standard care. Conclusions Adaptation to hemianopia is a personal journey with several factors being important for prediction of its presence, including MAC outcomes and extent of inferior visual field loss. A clinical recommendation is made for inclusion of the MAC as part of a functional assessment for hemianopia. Implications for rehabilitation The mobility assessment course (MAC) should be considered as an assessment of mobility/scanning in the rehabilitation of patients with homonymous hemianopia. A cut-off score of ≤25% omissions on MAC could be employed to determine those likely to adapt to hemianopia long-term. Targeted support and therapy for patients with significant visual loss in the inferior visual field area should be considered.

Methods for Prism Placement for Hemianopic Visual Field Loss in Adults with Low Vision

Several adult patients with low vision have come to the Advanced Low Vision Clinic at the Corporal Michael Crescenz Department of Veterans Affairs Medical Center (CMCVAMC), in Philadelphia, Pennsylvania, and to the Bucks County Association for the Blind and Visually Impaired, in Newton, Pennsylvania, with a diagnosis of hemianopic loss secondary to a stroke in the visual cortex; brain tumors; or traumatic brain injury. Prism placement for peripheral field loss allows patients to have enhanced peripheral awareness and an increased peripheral field depending on the type of prism used (Brillant, 1999). To determine prism placement, a low vision optometrist evaluates the patient. The evaluation consists of trials of different types of prism systems, including Fresnel, Gottlieb, Onufryk, and Eli Peli. When a preference for a particular prism system is shown, it is temporarily placed. The optometrist confers with the orientation and mobility (O&M) specialist to discuss patient goals and a plan of care. The O&M specialist performs an evaluation and provides visual scanning training as well as instruction in the functional use of prisms. This report describes the process used in these centers for assessing and placing the prism for these individuals. Prior to prism placement, a full visual field test is completed using a Zeiss, Octopus, or Goldman perimeter, which accurately define the visual field loss. The optometrist and O&M specialist review the results of this test to determine the plan of care for the patient. An Esterman visual field test is completed if the patient is interested in driving again. The Esterman test measures the visual field with both eyes open, as this is required by states that permit driving only if an individual has a visual field of 120 degrees across the horizontal meridian. Prism placement is first tested with a 20-40D Fresnel prism cut to the shape of the spectacle lens in the area of field loss with the prism's base facing in the direction of vision loss. The prism is placed by the optometrist to bisect the pupil so its edge can be seen without scanning into the prism. The edge is then trimmed with iridectomy scissors to the edge of the pupil. The patient then scans into the edge and is asked to count fingers within 10-15 degrees of the non-seeing field. The individual is then asked to ambulate and to detect objects in the non-seeing field. For example, if the non-seeing field is temporal, the scan would be to the left or right to view a painting on the wall, a doorway, or a person passing to the side. If the prism edge is causing diplopia, it is trimmed again to the edge of the dilated pupil. In another method of prism placement, an individual is asked to look straight ahead at his or her nose (if the nose can be seen). If they cannot see their nose, then they are asked to look towards the center of their face, then bring a Post-it note (a small self-adhesive piece of paper) along the plane of their glasses from the non-seeing area into the plane of where they can just see the edge of the Post-it note. They then move the Post-it note back 1 millimeter (mm) until they can no longer see it. When viewing straight ahead, they should not see the edge of the Post-it note. A permanent marker pen such as a Sharpie can then be used to mark the eyeglass lens for later placement of the Fresnel prism (Giorgi, Woods, & Peli, 2009). Choosing the strength of the prism depends on the size of the defect and the individual's tolerance. As a general rule of thumb, the number of degrees the image is moved is half the dioptric power of the prism. Therefore, a 30-diopter prism will move the image approximately 15 degrees. The base of the prism is always placed towards the area of the defect in order to move the image towards the seeing area. The base is marked on the Fresnel prism for orientation. The clinician places the prism to the edge of the defect as described above (Warren & Barstow, 2011). …

SV1. Non-invasive electrical brain stimulation in hemianopia and visual neglect

Non-invasive electrical brain stimulation is a promising add-on approach for neurorehabiliation of visual field loss and visual neglect. Transorbital alternating current stimulation (rtACS) has been used in clinical studies to improve visual functions in patients suffering vision loss after optic nerve damage. However, in hemianopic visual field loss the effects of rtACS are less distinct than after optic nerve damage. Combining visual field training with current stimulation may enhance training effects which has been already shown for anodal transcranial direct current stimulation (tDCS) of the occipital cortex in hemianopic visual field loss after strokes. Recent observations also indicate that rebalancing the activity between the two hemispheres as a functional mechanism accompanying recovery may be induced by lateralized respectively dual-mode tDCS application.

Correlation of OCT and Hemifield Pattern VEP in Hemianopia

Purpose: To analyze the correlation between RNFL thickness changes measured by OCT and hemifield pattern VEP in hemianopic visual field loss. Methods: Twelve eyes of six patients with hemianopia were studied. Two patients had bitemporal hemianopia caused by chiasmal tumor, one patient had inferior hemianopia caused by traumatic optic neuropathy, and three patients had homonymous hemianopia caused by occipital lobe lesions. The retinal nerve fiber layer thickness around the optic disc was measured by optical coherence tomography (OCT) and visual pattern evoked potentials were measured using hemifield stimulations. Results: Normal eyes of traumatic optic neuropathy patients were excluded from the analysis. The retinal nerve fiber layer thickness as measured by OCT corresponded to the visual field defect in 9 of 11 eyes (81.8%) and the hemifield pattern VEP response corresponded to visual field defect in 7 of 11 eyes (63.6%). Conclusions: RNFL thickness measurement by OCT and hemifield PVEP are useful in evaluation of patients with hemianopia. However, they should be performed with caution, and compared with various clinical examinations because of their incomplete correlation with visual field defects.

Bilateral Isolated Lateral Geniculate Body Lesions in a Patient with Pancreatitis and Microangiopathy

An 18-year-old woman developed pancreatitis and a thrombotic microangiopathy but no electrolyte abnormalities. She required intubation hours after admission and was not able to communicate for 8 days. Upon recovering consciousness, she reported severely impaired vision in both eyes, but ophthalmologic evaluation and neuroimaging were not obtained until several days later. Ophthalmologic examination documented retinal infarcts and profound binocular vision loss with hourglass bilateral homonymous hemianopic visual field loss. MRI showed signal abnormalities restricted to the area of the lateral geniculate bodies (LGBs) with characteristics most suggestive of hemorrhagic infarction. Very few cases of isolated bilateral LBG lesions have been reported. Damage has been attributed to myelinolysis from osmotic demyelination or to infarction from microvascular occlusion. This case conforms more to microvascular infarction. The vulnerability of the LGB to selective microvascular infarction may be based on a combination of its unique architecture and high metabolic demand.

Giant cell arteritis presenting with hemianopic visual field loss

Giant cell arteritis presenting with hemianopic visual field loss

Retinal eccentricity effects on reaction time to imagined stimuli

To cast light on the possible neural substrate of visual imagery we tested normal participants and one hemianopic patient on simple reaction time (RT) to real and imagined visual stimuli. In one experiment participants were to detect as quickly as possible a luminous square presented at one out of two different retinal eccentricities. A well known effect with visual stimuli is that RT is slower for peripheral versus central stimuli. We found that imagined stimuli showed an eccentricity effect similar to that obtained with real stimuli. However, this was not the case in a patient with a hemianopic visual field loss (quadrantanopia) as a result of damage to the optic radiation. Even though the patient showed no difficulty in imaging stimuli in the affected hemifield she did not show an eccentricity effect as was the case in her intact side. In a second experiment, normal participants showed faster RT to stimuli of larger size with either real or imagined stimuli. Overall, these results show that visual perception and imagination share a similar visuotopic organisation that is disrupted following deafferentation of the visual cortex.

Low vision rehabilitation and driving training for hemianopic visual field loss: two case reports

Licensure for driving requires 140° of horizontal visual field in many states including Texas. Consequently, patients with hemianopic field loss (HFL, < 90°) are precluded from driving regardless of visual acuity and compensatory scanning skills. This report describes two patients with homonymous hemianopia who developed compensatory scanning skills using different approaches and were both successful in obtaining a driver's license in Texas.

The Diagnostic Yield of the Evaluation for Isolated Unexplained Optic Atrophy

To report the diagnostic yield for the evaluation of isolated and unexplained optic atrophy. Two tertiary care academic neuroophthalmology clinics. Retrospective case series. Patients with optic atrophy. Retrospective review of all charts with the diagnosis of optic atrophy. Included patients were adults with isolated, but unexplained, optic atrophy. Patients were excluded if they were children, had incomplete or inadequate documentation of the findings, had nonneurologically isolated optic atrophy (e.g., other localizing findings), or had a history (e.g., prior neuroimaging study showed a compressive lesion, prior ischemic optic neuropathy) or examination (e.g., central retinal artery occlusion) evidence for an etiology for the optic atrophy. Results of diagnostic evaluation. A total of 1110 charts with the diagnosis of optic atrophy were reviewed from the 2 participating institutions (368 from the University of Cincinnati and 742 from the University of Iowa). Of these 1110 charts, 91 (8%) with isolated unexplained optic atrophy were included, and 1019 charts (92%) were excluded. Of 91 included patients, 18 (20%) had a compressive lesion causing optic atrophy, and 73 (80%) cases had no etiology for the optic atrophy on neuroimaging. Of the 18 patients with abnormal imaging (e.g., meningioma, pituitary adenoma, craniopharyngioma) studies, 11 had bilateral and 7 had unilateral optic atrophy. Five of the 18 patients had progressive visual loss, 3 had hemianopic visual field loss, and 11 were younger than 50 years old. Patients with optic atrophy in our study typically had historical or examination findings that led to an etiologic diagnosis. Neuroimaging showed an etiology in 20% of patients. Other laboratory testing did not produce an etiologic diagnosis in the absence of a suggestive history or examination. On the basis of our results, we recommend neuroimaging for all patients with unexplained optic atrophy and consideration for directed laboratory studies only.

Design for Simulator Performance Evaluations of Driving with Vision Impairments and Visual Aids

Driving simulator technology provides a safe method for evaluating the impact of vision loss on different components of the driving task and the potential efficacy of visual aids intended to compensate for a particular type of vision loss. Most previous investigations have used general driving scenarios. It is proposed here that scenarios with different task requirements be designed specifically to address the condition under investigation. As an example, the design of driving scenarios and tasks that are specific for the evaluation of one type of visual field loss, homonymous hemianopia, is described. Results of pilot studies show that even with a small sample size, the design is sufficiently sensitive to differentiate individuals with hemianopic visual field loss from control drivers. These results suggest that careful design of test situations, measurements, and analyses provides a strong basis for investigations of driving performance of individuals with specific types of vision impairment and could be used to evaluate the efficacy of low-vision driving aids.

Design for Simulator Performance Evaluations of Driving with Vision Impairments and Visual Aids

Driving simulator technology provides a safe method for evaluating the impact of vision loss on different components of the driving task and the potential efficacy of visual aids intended to compensate for a particular type of vision loss. Most previous investigations have used general driving scenarios. It is proposed here that scenarios with different task requirements be designed specifically to address the condition under investigation. As an example, the design of driving scenarios and tasks that are specific for the evaluation of one type of visual field loss, homonymous hemianopia, is described. Results of pilot studies show that even with a small sample size, the design is sufficiently sensitive to differentiate individuals with hemianopic visual field loss from control drivers. These results suggest that careful design of test situations, measurements, and analyses provides a strong basis for investigations of driving performance of individuals with specific types of vision impairment and could be used to evaluate the efficacy of low-vision driving aids.

Speed of progression of migrainous visual aura measured by sequential field assessment

Homonymous hemianopia can occur due to migraine, a clinical syndrome of unknown etiology. Cortical spreading depression (CSD) has been suggested to underlie migraine visual aura. Functional magnetic resonance imaging (fMRI) studies gives an estimate of the speed of the spread of this electrophysiological event (3.5 ± 1.1mm/min). Our observation of a changing hemianopic visual field loss was documented using a Humphrey visual field analyzer. Using this data and matching it with the retinotopic map of primary human visual cortex, an average speed of 3.65 mm/min was calculated. This finding reinforces previous studies that hypothesize CSD to be responsible for changes in visual function associated with migraine.

The Use of Fresnel and Ophthalmic Prisms with Persons with Hemianopic Visual Field Loss

The Use of Fresnel and Ophthalmic Prisms with Persons with Hemianopic Visual Field Loss

Patterns of hysterical hemianopia.

… hysteria behaves as though anatomy did not exist . . . -Freud (*RF reference 1*, p. 169) Every decade proclaims the death of hysteria, but simulated neurologic disorders continue to be common and confusing, if less fashionable than a century ago. Recognizing pseudoneurologic defects is particularly important in the current parsimonious era of medical cost-effectiveness. Hysterical signs represent the patient's conception of disease modified by suggestions from the examining physician. Diagnosis depends on recognition of the patient's nonanatomic patterns. Hysterical visual field loss, often confusing when tested by automated perimetry,2 can be recognized quickly using simple confrontation techniques. Because spurious field defects rarely coincide with anatomic reality, they are especially helpful in identifying suggestible patients. To delineate the patterns of hysterical hemianopic visual field loss, I analyzed my experienced with patients having spurious visual field defects. Patients. I reviewed my notes on inpatients with hysterical visual field defects, personally examined on the wards of the Los Angeles County/University of Southern California Medical Center during the past 25 years. Visual field examinations utilized double simultaneous finger-counting confrontation followed by centripetal presentation of moving fingers. Selected patients also were …

Effects of Age and Hemianopic Visual Field Loss on Driving

With the use of an interactive driving simulator, we examined the driving performance of older patients with either homonymous or quadrantic hemianopsia with primarily occipital lobe damage resulting from cerebrovascular accidents (CVA's). We compared the performance of these patients with that of a normally sighted, age-similar control group and that of a normally sighted younger group. The driving performance of the patients was either worse than, or similar to, that of the older control group; all of the older individuals (both patients and normally sighted subjects) had worse performance than the younger group. Age-related effects combined with the effects of visual field losses in older patients with cerebrovascular accidents had a negative impact on driving skills.

Augenveränderungen bei MELAS-Syndrom

The present paper reports on the clinical findings of a 34-year-old male patient with MELAS syndrome. MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis and strokelike episodes) belongs to a group of syndromes called mitochondrial encephalomyopathies that are characterized by changes of the mitochondrial respiratory chain and the histological finding of "ragged red fibers" in muscle biopsy. In our case the diagnosis was confirmed by multiple neurologic tests including muscle biopsy and biochemical analysis of the respiratory chain. The ocular findings included reversible, homonymous hemianopic visual field loss documented six years earlier, atypical retinitis pigmentosa with marked attenuation of the scotopic ERG, myopia and nuclear cataract of the right eye. An extracapsular cataract extraction with implantation of a posterior chamber lens was performed on the rigt eye, the course was unremarkable and vision improved. In dealing with patients presenting with ocular or neurologic signs indicating mitochondrial encephalopathy, the ophthalmologist should consider MELAS syndrome or any other of the mitochondrial encephalomyopathy syndromes as a possible etiology and take the necessary steps for further medical and neurologic evaluation of the patient.