Prevalence and characteristics of visual snow syndrome in a cohort of young Italian adults

Background: Visual snow (VS) and visual snow syndrome (VSS) are becoming increasingly recognized. However, their prevalence worldwide is unknown. This study aimed to investigate lifetime prevalence and describe the clinical characteristics of VS and VSS in a representative population sample from Italy. Methods: This cross-sectional study was conducted among students attending different faculties in three universities in the central and southern regions of Italy. Eligible participants completed a self-administered questionnaire. In patients fulfilling possible criteria for VS/VSS, the diagnosis was validated by an on-site visit conducted by experienced neurologists and neuro-ophthalmologists that included optical coherence tomography angiography (OCTA). Results: A total of 750 participants completed the study. Seven (0.9%) reported symptoms compatible with VS (mean age 24.8 ± 3.85 years). Among the seven patients, five (0.7%) also met the phenomenological and temporal criteria for VSS. Neuroimaging and ophthalmological examinations showed normal results upon review or during the on-site visit including OCTA. For the five patients with full VSS, the other visual symptoms reported were enhanced entoptic phenomenon (n = 5), photophobia (n = 5), palinopsia (n = 1), and nyctalopia (n = 4). In four of the seven patients (57%) reporting VS symptoms, there was a concomitant diagnosis of migraine with aura, and in one (14%) migraine without aura. All patients (n = 7) reported tinnitus. Six of the seven (85.7%) patients with VS/VSS had never used specific treatments for the condition. None of the seven patients had received a previous diagnosis of VS/VSS. Conclusions: The prevalence in Italy of VSS is around 1%. However, there is a limited tendency for affected individuals to seek medical attention, leading to a low rate of diagnosis and treatment.