Clinical reading-related oculomotor assessment in visual snow syndrome

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Purpose

Visual snow syndrome (VSS) is a complex neurological condition presenting with an array of sensory, motor, and perceptual dysfunctions and related visual and non-visual symptoms. Recent laboratory studies have found subtle, basic, saccadic-based abnormalities in this population. The objective of the present investigation was to determine if saccadic-related problems could be confirmed and extended using three common clinical reading-related eye movement tests having well-developed protocols and normative databases.

Methods

This was a retrospective analysis of 32 patients (ages 16–56 years) diagnosed with VSS in the first author's optometric practice. There was a battery of three reading-related tests: the Visagraph Reading Eye Movement Test, the Developmental Eye Movement (DEM) Test, and the RightEye Dynamic Vision Assessment Test, all performed using their standard documented protocols and large normative databases.

Results

A high frequency of oculomotor deficits was found with all three tests. The greatest percentage was revealed with the Visagraph (56%) and the least with the RightEye (23%). A total of 77% of patients failed at least one of the three tests.

Conclusion

The present findings confirm and extend earlier investigations revealing a high frequency of saccadic-based oculomotor problems in the VSS population, now including reading-related tasks. This is consistent with the more general oculomotor/motor problems found in these individuals.

Related collections

Most cited references 21

Record: found
Abstract: found
Article: not found

Microstimulation in visual area MT: effects on direction discrimination performance.

CD Salzman, CM Murasugi, KH Britten … (1992)

Physiological and behavioral evidence suggests that the activity of direction selective neurons in visual cortex underlies the perception of moving visual stimuli. We tested this hypothesis by measuring the effects of cortical microstimulation on perceptual judgements of motion direction. To accomplish this, rhesus monkeys were trained to discriminate the direction of motion in a near-threshold, stochastic motion display. For each experiment, we positioned a microelectrode in the middle of a cluster of neurons that shared a common preferred direction of motion. The psychophysical task was then adjusted so that the visual display was presented directly over the neurons' receptive field. The monkeys were required to discriminate between motion shown either in the direction preferred by the neurons or in the opposite direction. On half the trials of an experiment, we applied electrical microstimulation while monkeys viewed the motion display. We hypothesized that enhancing the neurons' discharge rate would introduce a directionally specific signal into the cortex and thereby influence the monkeys' choices on the discrimination task. We compared the monkeys' performance on "stimulated" and "nonstimulated" trials in 139 experiments; all trials within an experiment were presented in random order. Statistically significant effects of microstimulation were obtained in 89 experiments. In 86 of the 89 experiments with significant effects (97%), the monkeys indicated that motion was in the neurons' preferred direction more frequently on stimulated trials than on nonstimulated trials. The data demonstrate a functional link between the activity of direction selective neurons and perceptual judgements of motion direction.

0 comments Cited 82 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

‘Visual snow’ – a disorder distinct from persistent migraine aura

Christoph J. Schankin, Farooq H Maniyar, Kathleen B. Digre … (2014)

Patients with 'visual snow' report continuous tiny dots in the entire visual field similar to the noise of an analogue television. As they frequently have migraine as a comorbidity with ophthalmological, neurological and radiological studies being normal, they are offered various diagnoses, including persistent migraine aura, post-hallucinogen flashback, or psychogenic disorder. Our aim was to study patients with 'visual snow' to characterize the phenotype. A three-step approach was followed: (i) a chart review of patients referred to us identified 22 patients with 'visual snow'. Fifteen had additional visual symptoms, and 20 patients had comorbid migraine, five with aura; (ii) to identify systematically additional visual symptoms, an internet survey (n = 275) of self-assessed 'visual snow' subjects done by Eye On Vision Foundation was analysed. In two random samples from 235 complete data sets, the same eight additional visual symptoms were present in >33% of patients: palinopsia (trailing and afterimages), entoptic phenomena (floaters, blue field entoptic phenomenon, spontaneous photopsia, self-light of the eye), photophobia, and nyctalopia (impaired night vision); and (iii) a prospective semi-structured telephone interview in a further 142 patients identified 78 (41 female) with confirmed 'visual snow' and normal ophthalmological exams. Of these, 72 had at least three of the additional visual symptoms from step (ii). One-quarter of patients had 'visual snow' as long as they could remember, whereas for the others the mean age of onset was 21 ± 9 years. Thirty-two patients had constant visual symptoms, whereas the remainder experienced either progressive or stepwise worsening. Headache was the most frequent symptom associated with the beginning or a worsening of the visual disturbance (36%), whereas migraine aura (seven patients) and consumption of illicit drugs (five, no hallucinogens) were rare. Migraine (59%), migraine with aura (27%), anxiety and depression were common comorbidities over time. Eight patients had first degree relatives with visual snow. Clinical investigations were not contributory. Only a few treatment trials have been successful in individual patients. Our data suggest that 'visual snow' is a unique visual disturbance clinically distinct from migraine aura that can be disabling for patients. Migraine is a common concomitant although standard migraine treatments are often unhelpful. 'Visual snow' should be considered a distinct disorder and systematic studies of its clinical features, biology and treatment responses need to be commenced to begin to understand what has been an almost completely ignored problem.

0 comments Cited 65 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Microstimulation in visual area MT: effects of varying pulse amplitude and frequency.

CM Murasugi, CD Salzman, WT Newsome (1993)

We have previously shown that perceptual judgements of motion direction are based in part on the activity of direction selective neurons in extrastriate visual area MT (Salzman et al., 1990, 1992). In those experiments, we applied low-amplitude microstimulation pulses (10 microA, 200 Hz) to clusters of MT neurons whose preferred directions were similar. The effect of microstimulation was to bias the monkeys' choices on a direction discrimination task toward the preferred direction of neurons at the stimulation site. The results suggest that microstimulation generated a directionally specific cortical signal by activating selectively neurons near the electrode tip. To test this notion more directly, we have now examined the behavioral effects of varying current amplitude, current frequency, and electrode position. In the majority of experiments, the directional bias in the monkeys' choices was reduced or eliminated as current amplitude increased to 80 microA. In addition, 80 microA stimulating pulses frequently impaired overall performance as measured by the percentage of correct responses. This decrement in performance indicated that 80 microA pulses introduced "noise" into the neural circuitry encoding motion direction, presumably by increasing current spread to activate a larger population of neurons representing all directions of motion. In contrast, increasing current frequency to 500 Hz (10 microA pulses) preserved the directional specificity of microstimulation effects. The precise position of the stimulating electrode also influenced the magnitude of microstimulation effects; in some cases, differences in position on the order of 100 microns determined whether an experiment yielded a very large effect or no effect at all. Thus, directionally specific activation of cortical circuitry within MT can be disrupted by increases in current spread or by small changes in electrode position. These observations suggest that the effects of low-amplitude microstimulation depend upon direct activation of a well-localized population of neurons.

0 comments Cited 28 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Contributors

Barry Tannen

Journal

Journal ID (nlm-ta): J Optom

Journal ID (iso-abbrev): J Optom

Title: Journal of Optometry

Publisher: Elsevier

ISSN (Print): 1888-4296

ISSN (Electronic): 1989-1342

Publication date PMC-release: 01 November 2023

Publication date (Print): Apr-Jun 2024

Publication date (Electronic): 01 November 2023

Volume: 17

Issue: 2

Electronic Location Identifier: 100500

Affiliations

[a ]EyeCare Professionals, PC 1777 Kuser Road, Hamilton Square, NJ 08690, USA

[b ]SUNY State College of Optometry, New York, NY, USA

[c ]Gabrielle Family Vision Care, Kirkland, Washington, USA

Author notes

[* ]Corresponding author. drt@ 123456eyecareprofessionals.com

Article

Publisher Item ID: S1888-4296(23)00048-1 Publisher ID: 100500

DOI: 10.1016/j.optom.2023.100500

PMC ID: 10641535

PubMed ID: 37918058

SO-VID: 58d81f72-977e-4f23-92e8-103d5c3ba4df

License:

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Clinical reading-related oculomotor assessment in visual snow syndrome

Read this article at

Abstract

Purpose

Methods

Results

Conclusion

Related collections

Clinical Virtual Research Center Journal of Ophthalmology

Most cited references 21

Microstimulation in visual area MT: effects on direction discrimination performance.

‘Visual snow’ – a disorder distinct from persistent migraine aura

Microstimulation in visual area MT: effects of varying pulse amplitude and frequency.

Author and article information

Contributors

Journal

Affiliations

Author notes

Article

History

Categories

Comments

Comment on this article

Similar content 298

Cited by 1

Most referenced authors 116