Visual snow

2020 ◽  
pp. 530-534
Author(s):  
Gerrit L. J. Onderwater ◽  
Michel D. Ferrari
Keyword(s):  
Visual Field ◽  
Pharmacological Treatment ◽  
Chronic Condition ◽  
Clinical Phenotype ◽  
Pathophysiological Mechanism ◽  
Migraine Aura ◽  
Patient History ◽  
Entire Visual Field ◽  
Visual Disturbances ◽  
Rule Out

Visual snow is characterized by continuous visual disturbances in the form of countless tiny particles present in the entire visual field, often interpreted as television static. The visual disturbances are almost always accompanied by additional symptoms, including palinopsia, nyctalopia, photophobia, entoptic phenomenon, bilateral tinnitus, concentration problems, lethargy, and irritability. Visual snow has been linked to migraine and the migrainous aura. The clinical phenotype of visual snow clearly different from migraine; however, the co-occurrence with migraine (aura) might imply that both conditions share underlying pathophysiological mechanism(s). Visual snow is currently diagnosed on patient history alone, as additional investigations are typical normal and do not contribute to the diagnosis. However, ophthalmological investigation, neuroimaging, and, in selected cases, electroencephalography are recommend to rule out other disorders. Although self-limiting in some cases, visual snow typically remains a chronic condition that is very difficult to suppress with drug or non-pharmacological treatment.

Pediatric Visual Snow Syndrome (VSS): A Case Series

2019 ◽  
pp. 249-254
Author(s):  
Kenneth J. Ciuffreda ◽  
MH Esther Han ◽  
Barry Tannen
Keyword(s):  
Visual Field ◽  
Case Series ◽  
Therapeutic Interventions ◽  
Visual Condition ◽  
Visual Phenomena ◽  
Entire Visual Field ◽  
The Individual ◽  
Vision Therapy ◽  
Abnormal Visual

Visual snow syndrome (VSS) is a relatively rare, unusual, and disturbing abnormal visual condition. The individual perceives “visual snow” (VS) throughout the entire visual field, as well as other abnormal visual phenomena (e.g., photopsia). Only relatively recently has treatment been proposed (e.g., chromatic filters) in adults with VSS, but rarely in the pediatric VSS population (i.e., medications). In this paper, we present three well-documented cases of VSS in children, including their successful neuro-optometric therapeutic interventions (i.e., chromatic filters and saccadic-based vision therapy)

Occipitoparietal alpha-band responses to the graded allocation of top-down spatial attention

2014 ◽  
Vol 112 (6) ◽  
pp. 1307-1316 ◽  
Author(s):  
Isabel Dombrowe ◽  
Claus C. Hilgetag
Keyword(s):  
Visual Field ◽  
Spatial Attention ◽  
Brain Regions ◽  
Alpha Band ◽  
Top Down ◽  
Attentional Resources ◽  
Parietal Lobes ◽  
Visual Spatial ◽  
Entire Visual Field ◽  
Band Activity

The voluntary, top-down allocation of visual spatial attention has been linked to changes in the alpha-band of the electroencephalogram (EEG) signal measured over occipital and parietal lobes. In the present study, we investigated how occipitoparietal alpha-band activity changes when people allocate their attentional resources in a graded fashion across the visual field. We asked participants to either completely shift their attention into one hemifield, to balance their attention equally across the entire visual field, or to attribute more attention to one-half of the visual field than to the other. As expected, we found that alpha-band amplitudes decreased stronger contralaterally than ipsilaterally to the attended side when attention was shifted completely. Alpha-band amplitudes decreased bilaterally when attention was balanced equally across the visual field. However, when participants allocated more attentional resources to one-half of the visual field, this was not reflected in the alpha-band amplitudes, which just decreased bilaterally. We found that the performance of the participants was more strongly reflected in the coherence between frontal and occipitoparietal brain regions. We conclude that low alpha-band amplitudes seem to be necessary for stimulus detection. Furthermore, complete shifts of attention are directly reflected in the lateralization of alpha-band amplitudes. In the present study, a gradual allocation of visual attention across the visual field was only indirectly reflected in the alpha-band activity over occipital and parietal cortexes.

scholarly journals Brightness Perception Throughout the Entire Visual Field

2015 ◽  
Vol 99 (5) ◽  
pp. 258-262 ◽  
Author(s):  
Tasuku Watanuki ◽  
Hiroshi Takahashi ◽  
Takashi Irikura
Keyword(s):  
Visual Field ◽  
Brightness Perception ◽  
Entire Visual Field

Characteristics of migraine visual aura in Southern Brazil and Northern USA

Cephalalgia ◽  
2011 ◽  
Vol 31 (16) ◽  
pp. 1652-1658 ◽  
Author(s):  
Luiz Paulo Queiroz ◽  
Deborah Isa Friedman ◽  
Alan Mark Rapoport ◽  
R Allan Purdy
Keyword(s):  
Visual Field ◽  
Migraine With Aura ◽  
Descriptive Study ◽  
Migraine Aura ◽  
Southern Brazil ◽  
Visual Symptom ◽  
Blurred Vision ◽  
Visual Aura ◽  
Common Features ◽  
Gradual Onset

Background: Migraine aura, made up of one or more neurological symptoms arising from the cortex or brainstem, is a complex neurological phenomenon. Visual aura is the most frequent aura manifestation. Studying the subjective components of visual aura makes it possible to identify common characteristics. Objective: To thoroughly describe the characteristics of migraine visual aura in patients with migraine with aura. Methods: We performed a retrospective, descriptive study of the visual aura of 122 migraine patients collected at two headache clinics in the Americas. This study was designed to determine the characteristics of a typical visual aura. Results: The most common features of the visual aura in our study are that it occurs before the headache with a gap of less than 30 minutes, lasts 5 to 30 minutes, has a gradual onset, usually begins peripherally, is unilateral, and shimmers. Furthermore, the location of typical visual aura in the visual field has no fixed relationship to headache laterality, is slightly more often without color, and is often described as small bright dots and zigzag lines. Blurred vision, not typically considered to be an aura phenomenon of cortical origin, is in fact the most frequently reported visual symptom. Conclusions: Migraine visual aura is heterogeneous and pleomorphic, and some of our findings run contrary to common beliefs.

scholarly journals Visuospatial Attention and the Split Brain

Physiology ◽  
1997 ◽  
Vol 12 (5) ◽  
pp. 226-231
Author(s):  
G Berlucchi ◽  
GR Mangun ◽  
MS Gazzaniga
Keyword(s):  
Visual Field ◽  
Left Hemisphere ◽  
Right Hemisphere ◽  
Visuospatial Attention ◽  
Attentional Biases ◽  
Split Brain ◽  
Right Hemisphere Damage ◽  
Entire Visual Field ◽  
The Right

In callosotomy patients, the right hemisphere attends to the entire visual field, whereas the left hemisphere attends to the right field only. The occurence of rightward attentional biases, simulating a hemineglect from right hemisphere damage, suggests that in these patients visuospatial attention tends to be controlled by the left hemisphere.

Recent Advances in Understanding Peripheral Vision

1986 ◽  
Vol 30 (6) ◽  
pp. 601-603 ◽  
Author(s):  
Mark W. Cannon
Keyword(s):  
Visual Field ◽  
Spatial Pattern ◽  
Peripheral Vision ◽  
Pattern Perception ◽  
Recent Advances ◽  
Entire Visual Field

Recent experiments have revealed a considerable uniformity in the mechanisms mediating spatial pattern perception over the entire visual field.

scholarly journals A Rare Case of Unilateral Retinitis Pigmentosa

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Syntia Nusanti ◽  
Mohamad Sidik ◽  
Ari Djatikusumo ◽  
Elyas Aditya
Keyword(s):  
Visual Field ◽  
Retinitis Pigmentosa ◽  
Clinical Examination ◽  
Rare Case ◽  
Retinal Pigment ◽  
Multifocal Electroretinogram ◽  
Ophthalmological Examination ◽  
Secondary Causes ◽  
Rule Out

Introduction: Retinitis pigmentosa (RP) is a hereditary disorder that diffusely involve photoreceptor and retinal pigment epithelial (RPE). It is characterized by progressive visual field loss and abnormal ERG. Unilateral RP is a rare condition that is usually sporadic. Clinical presentation and ancillary test results are similar to bilateral RP, with only one eye affected. In making the diagnosis of unilateral RP, clinicians must be able to rule out secondary causes, document a normal ERG in the unaffected eye, and follow-up the patient for at least 5 years to rule out bilateral but asymmetric disease. the aim of this case report is how to diagnose a rare case unilateral RP from clinical examination and ancillary tests. Methods: We report a case of a 33-year-old female with slowly progressive restriction of visual field of the left eye in the last one year before admission. Ophthalmological examination of the left eye revealed bone spicules spreading to peripheral fundus. Visual field examination revealed severely constricted visual field of the left eye. The multifocal electroretinogram (mfERG) examination showed severely depressed ERG function with reduced foveal responses. The fellow eye was within normal limit. Results: Patient was diagnosed with unilateral RP and must be followed-up for at least five years to rule out bilateral yet asymmetric disease. Making diagnosis of unilateral RP become one of the challenging case. Clinicians must be able to rule out the secondary causes that also have unilateral pigmentary retinal degeneration. Conclusion: With a good clinical examination and some simple ancillary tests, we could correctly diagnose unilateral RP. However, in this case we still need five years follow up to rule out bilateral RP yet asymmetric disease.

scholarly journals Spherical arena reveals optokinetic response tuning to stimulus location, size, and frequency across entire visual field of larval zebrafish

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Florian Alexander Dehmelt ◽  
Rebecca Meier ◽  
Julian Hinz ◽  
Takeshi Yoshimatsu ◽  
Clara A Simacek ◽  
...  
Keyword(s):  
Visual Field ◽  
Frequency Tuning ◽  
Sample Stimulus ◽  
Visual Fields ◽  
Visual Space ◽  
Motion Vision ◽  
Optokinetic Response ◽  
Larval Zebrafish ◽  
Retinal Processing ◽  
Entire Visual Field

Many animals have large visual fields, and sensory circuits may sample those regions of visual space most relevant to behaviours such as gaze stabilisation and hunting. Despite this, relatively small displays are often used in vision neuroscience. To sample stimulus locations across most of the visual field, we built a spherical stimulus arena with 14,848 independently controllable LEDs. We measured the optokinetic response gain of immobilised zebrafish larvae to stimuli of different steradian size and visual field locations. We find that the two eyes are less yoked than previously thought and that spatial frequency tuning is similar across visual field positions. However, zebrafish react most strongly to lateral, nearly equatorial stimuli, consistent with previously reported spatial densities of red, green and blue photoreceptors. Upside-down experiments suggest further extra-retinal processing. Our results demonstrate that motion vision circuits in zebrafish are anisotropic, and preferentially monitor areas with putative behavioural relevance.

Faith Ringgold’s Story Quilts

2018 ◽  
pp. 196-213
Author(s):  
Hertha D. Sweet Wong
Keyword(s):  
African American ◽  
Visual Field ◽  
Square Functions ◽  
Art Gallery ◽  
Race And Gender ◽  
American Artist ◽  
History Of ◽  
Entire Visual Field ◽  
And Gender

African American artist Faith Ringgold’s oversized story quilts are painted and stitched image-text narratives on fabric intended to be hung on art gallery walls. In all her work she thematizes race and gender, part of her project to revise historical misrepresentations and generate more accurate depictions. This chapter discusses Ringgold’s various interventions in a long history of textual and visual domination, noting also Ringgold’s innovations: how quilt squares function simultaneously as individual images or texts and as part of the entire visual field. Each quilt square functions as a page, while a series of quilt squares can function also as a frame. The sets of relations between page and frame and between image and text are multiple and variable.

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