Data were only analysed after data collection was completed. All eligible participants that signed up during the advertisement period (between July and September 2020) were tested. The estimate was based upon an AMD simulation study which was similar in nature to the larger study conducted 13.
A large effect could increase the practical significance of the findings. Using G*Power 12, it was estimated that a minimum of 13 participants were required to provide sufficient power (0.90), at a significance level of α = 0.05, to detect a large effect. Furthermore, AMD simulations have replicated patterns of behaviour and difficulties experienced by AMD patients 9.Īn a priori power calculation was conducted to estimate the required number of participants for a larger study investigating the effects of simulated AMD on anxiety and stress levels in everyday activities (not reported here). While simulations may never wholly replicate a visual impairment (e.g., due to patient variability in symptom presentation underdeveloped compensatory strategies and lack of progressive visual decline) 9, thus far simulating vision loss has been a simple, yet valid approach to investigate the effects of visual impairments on cognition 10, 11. Since older adults with visual impairments are significantly more vulnerable to physical and mental comorbidities (i.e., Parkinson’s disease, dementia, hearing loss), a vision loss simulation with healthy, normally-sighted participants can more easily isolate vision-related effects on behaviour 8, 9.
#BLIND MOCA SCORE INTERPRETATION SERIES#
To highlight the importance of central vision for cognitive assessments, we simulated visual impairment with AMD simulation goggles, while participants completed a series of cognitive tasks. Critically, AMD is known to be underdiagnosed in the elderly, with an estimated 25% of eyes medically judged to be ‘normal’, actually having features of AMD and suboptimal vision 7. One leading cause of visual impairment is age-related macular degeneration (AMD), which may result in an irreversible loss of central vision 5 and can negatively impact tasks involving visual functioning including reading, driving and recognising faces 6. Given that the prevalence of visual impairment is only estimated to increase due to the aging population, researchers and clinicians focusing on ageing and neurodegenerative disorders need to pay close attention to the possibility that visual impairments may affect the scores of cognitive tests. In 2020, moderate to severe vision impairment affected approximately 200 million people over the age of 50 4. Indeed, vision impairments are often overlooked in research and clinical settings it has previously been estimated that reduced vision may be undetected in up to 50% of older adults 3.
On the other hand, impairments of a visual nature can be harder to recognise as there may be no clear indication of impaired visual function 2. For example, a language barrier can become quickly apparent if participants struggle to understand instructions or perform adequately on a written task. While some of these factors may be easier to identify, others are more elusive. However, these scores can be impacted by a range of factors not directly measured by tests, ranging from situational, personal, language to cultural factors 1. Such false attributions may have significant ramification for diagnosis and research on cognitive functioning.Ĭognitive tests scores inform research and diagnoses in aging and neurodegenerative disorders. When vision is not accounted for, low test scores may inaccurately indicate poor cognition. The findings highlight the importance of considering visual functioning when assessing cognitive function. In contrast, performance on the verbal fluency test were not statistically different between the simulated and normal vision conditions ( p = 0.78). Performance on the reaction time task significantly decreased ( p < 0.001) in the simulated age-related macular degeneration condition, by as much as 25 percentile ranks. Moderate to severe levels of age-related macular degeneration were simulated, with a set of goggles, in a sample of twenty-four normally sighted participants while they completed two cognitive tasks: a vision-dependent reaction time task and a vision-independent verbal fluency test. The purpose of this study was to demonstrate the negative consequences of visual impairments on cognitive tests performance. Yet conditions that are synchronous which ageing, including visual decline, are easily overlooked when interpreting cognitive test scores. The reliable assessment of cognitive functioning is critical to the study of brain-behaviour relationships.
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