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S. Foran, E. Chia, J.J. Wang, R.G. Cumming, P. Mitchell, Blue Mountains Eye Study; Relationship Between Visual and Cognitive Impairments: The Blue Mountains Eye Study . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1272.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine whether there is an independent relationship between visual and cognitive impairments in an older Australian population. Methods: The Blue Mountains Eye Study second cross-section examined 3509 participants, age 50+ years, during 1997-2000. Visual acuity was measured before and after subjective refraction using the ETDRS method; visual impairment was defined as a visual acuity <20/40 in the better eye. Cognitive impairment was measured using the Mini-Mental State Examination, and was defined as a score <24 out of 30. Multivariate analyses adjusted for age, sex and cognitive risk factors. Results: The prevalence of both non-correctable visual (2.7%) and cognitive (5.1%) impairments increased with age. Age-specific rates for non-correctable visual impairment were 0.5%, 0.5%, 3.1% and 15.4% in the age groups 50-59, 60-69, 70-79 and 80+ years; corresponding rates for cognitive impairment in these age groups were 1.8%, 2.7%, 6.7% and 17.6%. After adjusting for age, sex, current smoking, history of stroke, and excluding persons whom the examiner indicated that the visual acuity performance might have been lowered by dementia, cognitive impairment increased the odds of visual impairment based on best-corrected visual acuity (OR 2.6, 1.4-4.6). With the same adjustments, for every point decrease in the mini-mental score, there was roughly a 10% increased likelihood of visual impairment based on presenting visual acuity (OR 1.11, 1.07-1.17) and best-corrected visual acuity (OR 1.13, 1.06-1.20). Similarly, visual impairment based on presenting acuity and non-correctable visual impairment, significantly increased the odds of cognitive impairment (adjusted OR 2-2.6, excluding blind persons). Every line read correctly on the logMAR chart decreased the odds for cognitive impairment by around 20%. Presence of correctable visual impairment, however, was not associated with statistically significantly increased odds for cognitive impairment. Conclusions: This study suggests that cognitive impairment may be an independent risk factor for visual impairment. The mechanism of this is unclear but could be related to confounding in measurement of visual acuity by cognitive impairment.
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