Analysis of Retinal Structure and Electrophysiological Function in Visual Snow Syndrome: An Exploratory Case Series

Area of Science:

• Ophthalmology
• Neuro-ophthalmology
• Visual electrophysiology

Background:

• Visual snow (VS) is characterized by persistent, grainy visual distortions, often part of visual snow syndrome (VSS).
• The underlying pathophysiology of VS, particularly the role of retinal function, remains poorly understood.
• Limited research exists on structural and functional retinal abnormalities in individuals experiencing VS.

Purpose of the Study:

• To investigate potential retinal structural and electrophysiological abnormalities in patients with visual snow.
• To compare retinal function between individuals with VS/VSS and healthy control subjects.

Main Methods:

• A retrospective case series involving 8 subjects (7 with VSS, 1 with isolated VS) with no other ocular or neurological conditions.
• Evaluations included automated perimetry, optical coherence tomography (OCT), visual evoked potential (VEP), and full-field electroretinography (ffERG).
• VEP and ffERG data were statistically compared against age- and sex-matched controls.

Main Results:

• All VS subjects exhibited normal visual acuity, color vision, brain MRI, automated perimetry, and OCT parameters.
• VEP testing revealed normal P100 and N135 wave patterns.
• ffERG showed significantly greater mean b-wave amplitudes (light- and dark-adapted stimuli) and light-adapted flicker amplitudes in VS subjects compared to controls.

Conclusions:

• Individuals with VS and VSS demonstrate normal retinal structure but exhibit abnormal electrophysiological responses.
• Elevated b-wave and flicker amplitudes in ffERG suggest heightened responsiveness of rod and cone photoreceptors.
• These electrophysiological findings may offer insights into the pathophysiology of visual snow.