High prevalence of seasonal affective disorder among persons with severe visual impairment.

BACKGROUND Light severely affects the occurrence of seasonal affective disorder (SAD). AIMS To compare the prevalence of SAD in persons with severe visual impairment and persons with full sight, and in persons with severe visual impairment with or without light perception. METHOD This cross-sectional study assessed the Global Seasonality Score (GSS) and the prevalence of SAD among 2781 persons with visual impairment and 4099 persons with full sight using the Seasonal Pattern Assessment Questionnaire (SPAQ). RESULTS Respondents with visual impairment had significantly higher GSS and prevalence of SAD compared with full sight controls, P<0.001. Light perception respondents were more vulnerable to seasonal change than both full sight and no light perception respondents. CONCLUSIONS The study showed a highly significant association between visual impairment and SPAQ-defined SAD parameters, supporting the hypothesis that decreased retinal light input plays a role in the pathogenesis of SAD.