Study reveals ‘complexity’ of symptoms related to visual snow syndrome
Key takeaways:
- Causes of visual snow included mild traumatic brain injury and neurological disease.
- Symptoms ranged from photosensitivity and enhanced entopic imagery to tinnitus and migraine.
Patients with visual snow syndrome reported several visual and nonvisual symptoms, with most experiencing subjective reduction of snow when treated with chromatic tints, according to a study published in Optometry and Vision Science.
“The visual snow syndrome is a relatively new medical diagnosis,” researchers at State University of New York College of Optometry wrote. “It primarily refers to the presence of ‘visual snow’ across and in front of one’s visual field, which is a dynamic pixelated array overlaying the visual field of either a chromatic or achromatic nature, which could be either transiently or constantly occurring, for months or years.”
Researchers conducted a retrospective analysis of 40 patients aged 12 to 55 years with visual snow syndrome, all of whom received a comprehensive vision examination, cycloplegic refraction if necessary, visual fields and dilated fundus examination. Most patients were referred by medical professionals, including neurologists, optometrists and ophthalmologists.
According to results, visual snow was present for a mean 6.3 years. Researchers reported that 90% of participants experienced constant visual snow, with 73% experiencing monochromatic visual snow. The most common exacerbating conditions included dark or light surfaces, computer screens and printed books.
Researchers noted a wide range of etiologies for visual snow, with 48% stemming from mild traumatic brain injury, 25% from neurological diseases and 38% from multiple causes. Just over 12% of participants reported visual snow first appearing with COVID-19 infection.
Fifty percent of participants received no prior treatment, while 20% were unsuccessfully treated using prescribed medications, including lamotrigine and amantadine. Other treatments, such as gray sunglasses or herbal supplements, were reported in 43% of participants.
The most common primary symptoms were photosensitivity, enhanced entoptic imagery, palinopsia and impaired night vision, all of which were reported with high frequency. Photosensitivity and enhanced entopic imagery were reported in 83% of participants, and many experienced three of the four primary symptoms.
Secondary symptoms included tinnitus (73%) and migraines (60%), while balance problems, photopsia and phonophobia also were reported in more than 50% of patients.
Researchers also reported sensory-motor or perceptual concerns in the group, the most common of which were accommodative insufficiency (53%), convergence insufficiency (38%) and saccadic deficits (38%).
Most patients had been prescribed a chromatic tint to reduce visual snow, with participants reporting 15% to 100% reduction in this and other related symptoms.
“The present findings reveal the complexity of the abnormal sensory-motor-perceptual dysfunctions found in those with visual snow syndrome,” researchers wrote. “A careful case history and comprehensive vision examination are required to ascertain the basic symptoms and signs as well as functional ramifications.”
They continued: “A chromatic tint was found to reduce the perceived intensity of the visual snow in the majority of individuals (80%). However, further studies (eg, a randomized clinical trial) will be required to disambiguate any effect of a chromatic tint per se from a possible placebo contribution.”
Perspective
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Visual snow syndrome is a newer neurological condition that has gained recent interest and recognition, although it still lacks an ICD code, particularly from its secondary associations with brain injury and migraine. Because the main symptoms and diagnosis involve the presence of at least two visual phenomena, eye care providers are key to its identification and management.
This retrospective analysis from the SUNY group reinforces the high frequency of accommodative, vergence and/or saccadic dysfunctions in patients with visual snow syndrome. It also supports optometry’s unique role in managing the often-debilitating perceptual symptoms.
Specifically, chromatic tints — often used by optometrists for other conditions — appear to help reduce the subjective experience of “visual static.” It is a straightforward and relatively low-risk option to consider, particularly since the effectiveness of pharmacological treatment remains limited. Adjunctive management for any oculomotor, accommodative and vergence abnormalities may also help improve a patient’s quality of life.
As the paper mentions, evidence supporting the use of chromatic tints could be stronger with a more robust study design, specifically a larger sample size and the presence of control. This would be particularly helpful as some may view the use of tints as equivocal, including for visual snow syndrome.
References:
- Silva EM, et al. Eye (Lond). 2023;doi:10.1038/s41433-023-02435-w.
- ·van Dongen RM, et al. Neurology. 2019;doi:10.1212/WNL.0000000000007825.
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