Vision loss, cognitive decline and dementia—A narrative review article

Abstract

Introduction and aim: In view of the aging population it is crucial to identify modifiable risk factors for dementia. This narrative review article summarizes the evidence on the association between loss of vision and loss of cognition, two conditions common in old age. Methods: For this review article a literature search was conducted across several databases using MeSH terms and relevant studies on visual function and cognition were identified. To be included studies had to have longitudinally investigated the association between visual function and the incidence of dementia or cognition. Results: From the 7961 articles a multistage screening based on predefined criteria identified 16 relevant studies that investigated loss of vision as a risk factor for loss of cognition and dementia. Of these 14 could observe an association between poorer visual function and an increased loss of cognition or risk of dementia after adjusting for confounders. The strength of this risk was more pronounced in some studies depending on 1) the severity of the visual impairment (dose-response relationship) and 2) the simultaneous presence of hearing deficits. Discussion: Poorer visual function is associated with an increased risk of newly occurring cognitive loss and/or dementia. This highlights the clinical relevance of ophthalmological care in the prevention of cognitive loss and dementia. Evidence from interventional studies and larger longitudinal studies that assess other visual qualities apart from visual acuity is currently lacking.