ObjectivesThere has been increasing epidemiological research examining the association between vision impairment (VI) and cognitive impairment and how poor vision may be a modifiable risk factor for cognitive decline. The objective of this systematic review is to synthesise the published literature on the association of VI with cognitive decline, cognitive impairment or dementia, to aid the development of interventions and guide public policies pertaining to the relationship between vision and cognition.MethodsA literature search was performed with Embase, Medline and Cochrane library databases from inception to March 2020, and included abstracts and articles published in peer-reviewed journals in English. Our inclusion criteria included publications that contained subjective/objective measures of vision and cognition, or a diagnosis of VI, cognitive impairment or dementia. Longitudinal or cross-sectional studies with ≥100 participants aged >50 years were included. The search identified 11 805 articles whose abstracts underwent screening by three teams of study authors. Data abstraction and quality assessment using the Effective Public Health Practice Project Quality Assessment Tool were performed by one author (NN). 10% of the articles underwent abstraction and appraisal by a second author (LA/VV), results were compared between both and were in agreement.Results110 full-text articles were selected for data extraction, of which 53 were cross-sectional, 43 longitudinal and 14 were case–control studies. The mean age of participants was 73.0 years (range 50–93.1). Ninety-one (83%) of these studies reported that VI was associated with cognitive impairment.ConclusionOur systematic review indicates that a majority of studies examining the vision–cognition relationship report that VI is associated with more cognitive decline, cognitive impairment or dementia among older adults. This synthesis supports the need for additional research to understand the mechanisms underlying the association between VI and cognitive impairment and to test interventions that mitigate the cognitive consequences of VI.

Introduction: There are no standard practices for considering sensory impairment in studies measuring cognitive function among older adults. Exclusion of participants with impairments may inaccurately estimate the prevalence of cognitive impairment and dementia. Methods:We surveyed prospective cohort studies measuring cognitive function in older adults, determined the proportion that excluded participants based on sensory impairment and the proportion that assessed each type of sensory impairment, and described the methods of sensory assessment.Results: Investigators/staff from 85 (of 192 cohorts) responded; 6 (7%) excluded participants with severe impairment; 80 (94%) measured hearing and/or vision impairment, while 5 (6%) measured neither. Thirty-two (38%) cohorts assessed hearing objectively and 45 (53%) assessed vision objectively.Discussion: Findings indicate variation in methods used to assess sensory impairment, with potential implications for resource allocation. To ensure equitable inclusion of study participants, consensus is needed on best practices standardized protocols for assessment and accommodations of sensory impairment.

Despite the high prevalence of sensory impairment in older adults, there are no standard practices for its consideration in cognitive studies. We conducted a systematic review to identify and survey prospective cohort studies collecting cognitive data in older adults in order to determine whether and how hearing and vision were considered. Among 81 cohorts that responded, 30 (37%) objectively assessed hearing, with audiometry as the most frequently-used method; 61 (75%) used patient-report and 12 (15%) used provider-report to subjectively assess hearing. Forty-one (51%) cohorts objectively assessed vision, half of which measured distance or near visual acuity; 55 (68%) used patient-report and 10 (12%) used provider-report to subjectively assess vision. Nineteen (23%) cohorts offered hearing accommodations and 30 (37%) offered vision accommodations during cognitive testing. Findings indicate variation in methods used to assess hearing and vision as well as in accommodation practices that could impact estimates of cognition among older adults.