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    1 Comment for this article
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    RE: Association between visual impairment and decline in cognitive function in a multiethnic Asian population
    Tomoyuki Kawada, MD | Nippon Medical School
    Lim et al. conducted a prospective study to examine the association between visual impairment (VI) and cognitive decline (1). The authors defined VI as presenting visual acuity worse than 20/40 based on the better-seeing eye, and cognitive function was assessed by Abbreviated Mental Test (AMT) score. The leading causes of VI were under-correction of refractive error and cataract, which could be mostly treatable. Standardized regression coefficients (SRC) of baseline VI for a decrease in AMT score over 6 years was -0.27 (95% confidence interval [CI], -0.37 to -0.17). In addition, SRC of unchanged or deteriorated VI for a decrease in AMT score over 6 years was -0.29 (95% CI, -0.40 to -0.18). They concluded that poor vision was independently associated with cognitive decline. I have some concerns.

    First, Varadaraj et al. investigated the association between near vision impairment (NVI) and frailty with propensity score adjustment (2), and concluded that NVI was significantly associated with severity of frailty. In addition, Swenor et al. reported that severity of visual impairment was significantly related to frailty (3). As frailty and cognitive impairment was closely associated, I recommend Lim et al. including frailty as an adjusting independent variable for the analysis.

    Regarding cognitive decline, Swenor et al. observed that participants with impaired visual acuity, contrast sensitivity, and stereo acuity were at risk for incident cognitive impairment (4). Visual impairment is closely associated with aging, disability and other geriatric problems, and comprehensive analysis including mental and physical problems should be conducted for predicting cognitive decline.

    The significant association and high screening ability of indicators are separate concept (5). Risk reduction of frailty and cognitive decline via maintenance of visual acuity should be verified by an interventional study.


    References
    1. Lim ZW, Chee ML, Da Soh Z, et al. Association between visual impairment and decline in cognitive function in a multiethnic Asian population. JAMA Netw Open. 2020;3(4):e203560. doi: 10.1001/jamanetworkopen.2020.3560
    2. Varadaraj V, Lee MJ, Tian J, et al. Near vision impairment and frailty: Evidence of an association. Am J Ophthalmol. 2019;208:234-241. doi: 10.1016/j.ajo.2019.08.009
    3. Swenor BK, Lee MJ, Tian J, et al. Visual impairment and frailty: Examining an understudied relationship. J Gerontol A Biol Sci Med Sci. 2020;75(3):596-602. doi: 10.1093/gerona/glz182
    4. Swenor BK, Wang J, Varadaraj V, et al. Vision impairment and cognitive outcomes in older adults: The Health ABC Study. J Gerontol A Biol Sci Med Sci. 2019;74(9):1454-1460. doi: 10.1093/gerona/gly244
    5. Bongue B, Buisson A, Dupre C, et al. Predictive performance of four frailty screening tools in community-dwelling elderly. BMC Geriatr. 2017;17(1):262. doi: 10.1186/s12877-017-0633-y
    CONFLICT OF INTEREST: None Reported
    READ MORE
    Original Investigation
    Ophthalmology
    April 23, 2020

    Association Between Visual Impairment and Decline in Cognitive Function in a Multiethnic Asian Population

    Author Affiliations
    • 1Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
    • 2Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
    • 3Duke-NUS Medical School, Singapore
    • 4Memory Aging and Cognition Centre, National University Health System, Singapore
    • 5Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore
    • 6Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore
    JAMA Netw Open. 2020;3(4):e203560. doi:10.1001/jamanetworkopen.2020.3560
    Key Points español 中文 (chinese)

    Question  Was there an association between visual impairment and decline in cognitive function over a 6-year period in a multiethnic Asian population?

    Findings  In this population-based cohort study of 2478 elderly Asian people, visual impairment at baseline and deterioration of vision over time were associated with decline in cognitive function over 6 years. The main causes of visual impairment among individuals with substantial cognitive decline were undercorrected refractive error and cataract, both of which are usually preventable or treatable.

    Meaning  Early intervention of visual impairment in elderly individuals may potentially mitigate decline in cognitive function.

    Abstract

    Importance  With the rapidly aging population, the burden of visual impairment (VI) and cognitive decline is expected to increase. Previous cross-sectional studies suggest an association between these 2 health outcomes. However, few longitudinal reports have examined this association, and to our knowledge, no studies have been performed in Asian populations. Further investigation on this association may help to better identify individuals at risk of cognitive decline.

    Objective  To examine the longitudinal association between VI and decline in cognitive function in a multiethnic Asian population.

    Design, Setting, and Participants  In this longitudinal, population-based, prospective cohort study, Chinese, Indian, and Malay adults 60 years or older at baseline were recruited from the Singapore Epidemiology of Eye Diseases (SEED) study. At baseline, participants from the SEED study were recruited under 3 studies: the Singapore Malay Eye Study (SiMES; 2004-2006), the Singapore Indian Eye Study (SINDI; 2007-2009), and the Singapore Chinese Eye Study (SCES; 2009-2011). Eligible participants were reexamined after 6 years (2011-2013 for SiMES, 2013-2015 for SINDI, and 2015-2017 for SCES). Data analysis was performed from November 1 to 24, 2019.

    Exposures  Visual impariment was defined as presenting visual acuity worse than 20/40 based on the better-seeing eye.

    Main Outcomes and Measures  Cognitive function was assessed using a locally validated Abbreviated Mental Test (AMT). The association between baseline VI and change in AMT score was determined using the multivariable linear regression model adjusting for baseline age; sex; race/ethnicity; presence of diabetes, hyperlipidemia, hypertension, and chronic kidney disease; history of cardiovascular disease; smoking status; alcohol intake; body mass index; educational status; and AMT score.

    Results  A total of 2478 individuals (1256 [50.7%] male; 1073 Chinese, 768 Indian, and 637 Malay adults) with mean (SD) age of 67.6 (5.6) years were evaluated, of whom 489 (19.7%) had reduction in AMT scores over 6 years. Baseline VI was associated with a decrease in AMT score over 6 years (β = −0.27; 95% CI, −0.37 to −0.17; P < .001). When change in vision over 6 years was evaluated, unchanged or deteriorated VI was associated with a decrease in AMT score over 6 years (β = −0.29; 95% CI, −0.40 to −0.18; P < .001). Among individuals with baseline VI and a substantial decrease in AMT score of 3 units or more over 6 years, the leading causes of VI were undercorrected refractive error (14 [45.2%]) and cataract (11 [35.5%]).

    Conclusions and Relevance  In this study, poor vision was independently associated with a decline in cognitive function. Causes of visual loss in these cases were mostly preventable, further suggesting that preserving good vision may be an important interventional strategy for mitigating cognitive decline.

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