Understanding Visual Snow Syndrome
Visual Snow and Visual Snow Syndrome (VSS) are not new phenomena, but both conditions have gained awareness over the last few years. VSS can significantly impact patients’ quality of life. This article aims to illuminate the clinical presentation, pathophysiology, and management strategies for this intriguing condition.
What is Visual Snow Syndrome?
Visual Snow is a neurological symptom characterized by a continuous, static-like visual disturbance that can resemble the “snow” seen on an untuned television screen. Unlike other visual disturbances, this static occurs continuously, even in dim light or when the eyes are closed. Visual snow when accompanied by a variety of other symptoms below, would create the diagnosis of Visual Snow Syndrome:
•Palinopsia (afterimages or trailing images)
•Photophobia (light sensitivity)
•Nyctalopia (difficulty seeing at night)
•Entoptic phenomena (seeing floaters, seeing colors, entoptic phenomenon, or self-light of the eye)
Clinical Presentation
Patients with VSS typically present with a constellation of visual symptoms that are persistent and bilateral. These may include:
1.Visual Static: The hallmark symptom of VSS is the presence of small flickering dots across the entire visual field. These dots may vary in size, intensity, and color, and they do not resolve with eye closure.
2.Light Sensitivity and Afterimages: Patients often report heightened sensitivity to light (photophobia), and some experience palinopsia, where afterimages of objects persist for an abnormal length of time (AKA “trails”).
3.Other Entoptic Phenomena: Visual snow can be accompanied by seeing visual phenomena such as floaters, flashes of light, or the visual perception of blood flow through retinal vessels (blue field entoptic phenomenon).
4.Headaches or Migraines: A significant number of patients with VSS also experience migraines, particularly with aura, although not all do.
Pathophysiology: What Causes Visual Snow?
The exact cause of VSS remains unclear, but research suggests that it is a neurological condition rather than an ocular issue. Studies using advanced imaging techniques, such as functional MRI, have indicated abnormal hyperexcitability in the visual cortex and other areas of the brain involved in visual processing. Individuals with VSS have been found to have increased grey matter.
Many patients with VSS report that their symptoms began after a migraine episode, another neurological event, a concussion or acquired brain injury, or a medication adverse reaction. There does appear to be a connection between anxiety-like tendencies and sensory sensitivities, which are also very common with concussion.
Diagnosing Visual Snow Syndrome
Diagnosis of VSS is clinical and often a diagnosis of exclusion. It is important for optometrists to be aware of the diagnostic criteria, which were proposed by Schankin et al. in 2014. According to these criteria, VSS should be diagnosed when patients have:
1.Visual Snow: A continuous visual disturbance, resembling static, across the entire visual field.
2.Additional Visual Symptoms: At least two of the following must be present:
•Palinopsia
•Photophobia
•Nyctalopia
•Enhanced entoptic phenomena (floaters, blue field entoptic phenomenon, etc.)
3.Persistence of Symptoms: Symptoms must be present for at least three months and cannot be attributed to another disorder, such as migraines or retinal disease.
We must first rule out any underlying ocular pathology, such as retinal disease, optic neuropathy, or refractive issues, before considering a diagnosis of VSS. A thorough vision examination, including imaging when appropriate, should be performed to rule out any structural causes for the visual symptoms.
Managing Visual Snow Syndrome
Unfortunately, there is currently no definitive cure for VSS, and management is largely symptom management. However, the following approaches can help improve the quality of life for patients:
1.Patient Education and Reassurance: Many patients with VSS have seen multiple specialists and undergone numerous tests before receiving a diagnosis. Reassuring the patient that the condition is not degenerative and does not lead to vision loss is critical for alleviating anxiety.
2.Tinted Lenses: Some patients report improvement in symptoms, particularly photophobia, with the use of FL-41 or other tinted lenses designed to reduce light sensitivity. While not a universal solution, it can provide relief for certain individuals.
3.Medication: Though no medications are specifically approved for VSS, treatments commonly used for migraines or epilepsy, such as lamotrigine or topiramate, have shown promise in some cases. However, these medications have side effects. Referral to a neurologist for medication management may be appropriate for patients with severe symptoms.
4.Vision Therapy: Although not a primary treatment, some patients benefit from visual rehabilitation techniques, especially if their symptoms include convergence insufficiency or other binocular vision anomalies. Peripheral awareness strategies can be helpful to stimulate the parasympathetic system.
5.Migraine Management: Since many patients with VSS also experience migraines, controlling migraine frequency and severity with lifestyle changes and medications may also help alleviate visual snow symptoms.
6. Stress reduction: Because there appears to be a link between VSS and heightened sympathetic nervous system response, strategies such as breathing, stress reduction, CBT and addressing anxiety can be helpful.
The Role of the Optometrist
Neuro optometry plays a crucial role in identifying VSS and guiding patients through their treatment journey. Because many patients experience significant frustration and fear about their unexplained symptoms, providing an accurate diagnosis and a management plan can greatly improve their psychological and emotional well-being.
The interdisciplinary nature of VSS management often requires collaboration with neurologists, and sometimes psychology and psychiatry, as well as other health care providers. Early recognition of the condition and appropriate referral can ensure patients receive the comprehensive care they need. Visual Snow Syndrome is a complex and often misunderstood condition, but with greater awareness, patients can have improvements in quality of life.
References:
Ciuffreda KJ, Tannen B, Rutner D, Han ME. Neuro-optometric treatment for visual snow syndrome: recent advances. Concussion. 2023 May 30;8(3)
Schankin CJ, Maniyar FH, Digre KB, Goadsby PJ. “Visual Snow” – A Disorder Distinct from Persistent Migraine Aura. Brain. 2014.
Puledda F, Ffytche D, O’Daly O, et al. Disrupted Cortical Connectivity in Visual Snow Syndrome: A Functional MRI Study. Brain. 2020.
Aeschlimann, Sarah A.∗; Klein, Antonia∗; Schankin, Christoph J.. Visual snow syndrome: recent advances in understanding the pathophysiology and potential treatment approaches. Current Opinion in Neurology 37(3):p 283-288, June 2024.
