The study in this issue of JAMA Ophthalmology by Patel and colleagues1 examines an important question: do coexisting conditions, such as dementia, worsen the functionality of those with visual impairment (VI)? The authors used data from the National Health and Aging Trends Study (NHATS), an ongoing cohort study assessing Medicare beneficiaries, and found that individuals with dementia and VI were less functional in each of 3 domains (mobility, self-care, and household activities) than those with either condition alone. Moreover, individuals with both dementia and VI had even greater functional impairment than would be expected by combining the associations of VI and dementia, an interaction resulting in particularly poor functionality.1 While both those with dementia and those with VI had limitations in mobility, self-care, and household activities, those with VI and probable dementia had scores nearly 50% lower than those without these conditions for all activity limitations evaluated.