June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Anomalous temporal integration and segregation in visual snow syndrome
Author Affiliations & Notes
  • Cassandra Brooks
    Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Yu Man Chan
    Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Joanne Fielding
    Department of Neurosciences, Central Clinical School, Monash University, Melbourne, Victoria, Australia
  • Owen B White
    Department of Neurosciences, Central Clinical School, Monash University, Melbourne, Victoria, Australia
  • David R Badcock
    School of Psychological Science, The University of Western Australia, Crawley, Western Australia, Australia
  • Allison M McKendrick
    Lions Eye Institute, The University of Western Australia, Perth, Western Australia, Australia
    Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Footnotes
    Commercial Relationships   Cassandra Brooks None; Yu Man Chan None; Joanne Fielding None; Owen White None; David Badcock None; Allison McKendrick None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 5329. doi:
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    • Get Citation

      Cassandra Brooks, Yu Man Chan, Joanne Fielding, Owen B White, David R Badcock, Allison M McKendrick; Anomalous temporal integration and segregation in visual snow syndrome. Invest. Ophthalmol. Vis. Sci. 2023;64(8):5329.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Visual snow syndrome (VSS) is a neurological condition named after a visual disturbance consisting of tiny, dynamic dots. However, diagnosis requires additional symptoms such as palinopsia (afterimages and/or trailing). In an observational, cross-sectional study, we tested the hypothesis that those with VSS have an increased tendency to integrate rather than segregate successive visual stimuli.

Methods : We tested temporal integration and segregation ability in 20 controls (aged 19 - 42, mean 27.6 years) and 26 people with VSS (aged 19 - 39, mean 28.5 years). Complimentary parts (Figure 1A) of a 4 x 4 grid of elements (0.5° element width and separation) were presented for 12ms each separated by a variable blank interstimulus interval (ISI). The grid contained a missing element that was identifiable if successive images were integrated and an odd element that appeared as two successive half circles if the images were segregated. In separate blocks, participants located the missing or odd element in a method of constant stimuli. Nine ISIs were tested (12, 24, 35, 47, 59, 71, 82, 94, 106ms) with 20 repeats each. Logistic psychometric functions were fit to individual data for each task to extract 50% correct thresholds, which were analysed using a repeated measures ANOVA with task and group as factors.

Results : There was a significant interaction between group and task (F(1,44)=12.96, p<0.001, ηp2=0.23, Figure 1B), with threshold ISIs that were longer in those with VSS compared to controls for the missing-element task (F(1,44)=4.97, p=0.031, ηp2=0.10, mean difference and 95% CI 12.85 [1.24 - 24.47]), indicating integration at longer ISIs. However, threshold ISIs were shorter for the odd-element task in VSS (F(1,44)=7.77, p=0.008, ηp2=0.15, mean difference and 95% CI -7.31 [-12.60 - -2.02]), signifying segregation at shorter ISIs. Individuals with prolonged integration did not exhibit poor segregation, as task thresholds were not correlated (controls: r=0.38, p=0.098; VSS: r=0.19, p=0.35).

Conclusions : Our results indicate measurable differences in temporal processing in VSS. The VSS group either continued to integrate despite longer gaps between successive stimuli, or if the task required, segregate stimuli that were in close succession. Prolonged temporal integration in VSS may relate to symptoms of palinopsia.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1A) Task procedure B) Mean thresholds and 95% CI for each group

Figure 1A) Task procedure B) Mean thresholds and 95% CI for each group

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