Visual Snow Symptoms May Reduce With Chromatically Tinted Lens Use

Visual snow symptoms may reduce in perceived intensity when individuals with the condition use a chromatically tinted lens, according to research published in Optometry & Vision Science. In some cases, the use of 2 or more tints under different lighting conditions may be beneficial.

Researchers retrospectively analyzed data from 40 patients (60% women; mean age, 28.9 years) with a diagnosis of visual snow syndrome during a 4-year period. Patients underwent a visual examination, cycloplegic refraction, if necessary, visual field assessment, and dilated fundus exam. The team obtained clinical data, including medication use, and participants reported visual and non visual symptoms using the Visual Snow Syndrome Symptoms Survey. The investigation examined etiologies, factors exacerbating the disorder, primary and secondary visual snow symptoms, and treatment options. 

Study participants underwent intuitive colorimetry assessment to determine a reference tint for testing. During a subjective chromatic tint assessment, patients performed viewing tasks at 40, 100, and 600 cm with fluorescent overhead illumination (350 lux). After walking in a hallway, viewing a computer screen, and observing objects on a wall, the cohort selected their preferred filter to reduce visual snow symptoms.

Overall, subjectively-reported data shows that visual snow is frequently constant and monochromatic, and presented an average of 6.43 years among the study participants. Bright and dark surfaces, which included computer screens, tended to exacerbate visual snow symptoms and the report identified mild traumatic brain injury as the most common etiology. Photosensitivity and tinnitus are the most common primary and secondary symptoms, respectively, according to the report. 

Oculomotor deficits, especially accommodative and vergence insufficiency, frequently accompany visual snow syndrome (~40-50%), the report shows. A total of 80% of the study participants initiated treatment with a chromatic tint, resulting in a subjective reduction of visual snow symptoms ranging from 15 to 100% (mean, 45%).

Because the study authors consider visual snow to be a relatively new medical condition, they highlight the need for more research and uniform protocols. 

“[T]here is a need to develop a specific, detailed, standardized protocol for the testing and prescribing of a chromatic tint in this population that extends beyond the well-established intuitive colorimeter protocol,” the researchers explain. “Currently, one does not exist. However, in the present study, and in a related, recently completed one, a common theme was to assess the efficacy of a chromatic tint under the most provocative/exacerbating condition(s), which allows for better direct comparison of the respective findings.”

Study limitations include a small sample size, a lack of a formal therapy protocol for visual snow, and the lack of a placebo control group.