Visual impairment (VI) is associated with an increased risk of dementia, especially in patients with worse visual acuity, according to study results published in the American Journal of Ophthalmology. These findings underscore the importance of visual screening and effective treatment for VI.
The study reports that the current understanding of the association between VI and risk of incident dementia is poor. Previous studies may have failed to present the association between VI and incident dementia due to small sample size, self-disclosure of visual function, a focus on late-onset dementia, and bias regarding the identification of dementia cases. Therefore, investigators from China and Australia, sought to explore the relationship between VI and its severity with incident dementia.
A total of 117,187 participants (age range: 40-69 years, 54.4% women) from the UK Biobank Study (2006-2010) without dementia at baseline were included. The researchers defined VI as habitual distance visual acuity worse than 0.3 logMAR in the better-seeing eye. Electronically linked hospital inpatient and deaths records were used to determine incident dementia in the participants.
During a median follow up of 5.96 years, after adjusting for potential confounders, the presence of VI was significantly associated with a higher risk of incident dementia (HR=1.78, 95% CI: 1.18-2.68, P =.006).
The investigators observed an apparent trend between VI severity and the risk of dementia (P for trend =.002). The highest risk for dementia was associated with severe VI (HR=3.53, 95% CI: 1.31-9.49, P =.013).
This study reports several limitations. Only the association between baseline visual acuity and the risk of dementia was investigated. Additionally, causes of VI were not available. Lastly, causal inferences could not be drawn, and the possibility of misclassification of covariates and residual confounding cannot be excluded.
These data indicated that individuals with VI are associated with greater risk of developing incident dementia, suggesting that VI may be a modifiable risk factor for dementia.
Zhu Z, Shi D, Liao H, et al. Visual impairment and risk of dementia: the UK biobank study. Am J Ophthalmol. Published online August 22, 2021. doi:10.1016/j.ajo.2021.08.010