Prevalence of visual snow and relation to attentional absorption

Abstract

Visual snow is a condition of unclear prevalence characterized by tiny flickering dots throughout the entire visual field. It appears to result from visual cortex hyperactivity and possibly correlates with propensity to be engrossed in sensory and imaginary experiences (absorption). The prevalence and correlates of visual snow, and emotional reactions to it, were explored in the general Portuguese population with three studies with online surveys. In Study 1, 564 participants were shown an animated graphic simulation of visual snow and asked to rate how frequently they have similar percepts on a scale anchored by 0% and 100% of their waking time. They also reported their degree of distress and fascination resulting from visual snow. Absorption was measured with the Modified Tellegen Absorption Scale. 44% of respondents reported they see visual snow at least 10% of the time, and 20% reported seeing it between 80% and 100% of the time. Similar to findings in clinical samples, the frequency of visual snow correlated with tinnitus frequency and entoptic phenomena, but not with ophthalmologic problems. It was confirmed that visual snow is related to absorption. Although distress caused by visual snow was generally absent or minimal in our samples, a substantial minority (28%) reported moderate to high levels of distress. High fascination with visual snow was reported by 9%. In Studies 2 and 3, visual snow was measured by means of verbal descriptions without graphic simulation (“visual field full of tiny dots of light” and “world seen with many dots of light”, respectively). The results were similar to those in Study 1, but seeing visual snow 80%-100% of the time was less frequent (6.5% in Study 2 and 3.6% in Study 3). Visual snow has been insufficiently investigated. More research is needed to uncover underlying neurophysiological mechanisms and psychological and behavioral correlates.

Elucidating the Visual Snow Spectrum: A Latent Class Analysis Study

“…Our results show some similarities to existing work in the field and indicate that both visual snow and other perceptual phenomena associated with VSS are common perceptual experiences. For example, the percentage of our participants who experienced visual snow at least some of the time is remarkably similar to the findings of Costa et al, whose work shows that 44% of people experience visual snow at least 10% of the time [6]. Meanwhile, 41.92% of our participants reported experiencing visual snow some of the time.…”

“…As there is currently no objective measure of VSS severity, clinicians and researchers must evaluate people's own descriptions of the impact of their perceptual experiences. Our work, along with that of Costa et al, shows that it is possible to experience numerous visual snow spectrum phenomena in the absence of either visual snow itself, and in the absence of negative impacts [6]. As such, the question remains: what causes visual phenomena to be-or become-distressing?…”

“…Research to date has not investigated whether the visual snow spectrum might extend beyond the existing diagnostic criteria, to include a range of normal perceptual experiences in the general population. Several recent studies have provided evidence that both visual snow and VSS are somewhat common in the general population; around 40% of people experience visual snow at least some of the time, while a 2020 prevalence estimate shows that 2.2% of people meet the diagnostic criteria for VSS without prior knowledge [6,7,9]. These studies suggest that both lifelong and undiagnosed VSS may be highly prevalent and that VSS may not always have noticable impacts on the people who experience it.…”

“…Research has often described VSS as a spectrum-based disorder because it is associated with a range of perceptual experiences and levels of severity [4,5]. People with confirmed (i.e., medically or self-diagnosed) VSS experience a variety of different impacts, from minor annoyance or fascination, to major disruptions to quality of life [3,6]. The number of additional symptoms experienced, and the frequency with which these are experienced, also varies substantially between patients [4,7].…”

Improving Understanding of Visual Snow by Quantifying its Appearance and Effect on Vision

“… 24 In this study, the average size match was a 6 second of arc simulation dot, which is expected to produce a retinal image a few minutes of arc in size, assuming an equivalent blur of 0.25 D (the standard tolerance for a clinical refraction 25 ). Second, visual snow simulations have also previously been used to estimate prevalence 26 and in neuroimaging research. 27 – 29 Images illustrating visual snow have been generated using text-to-image artificial intelligence (AI) 30 and a smartphone app.…”