Abstract
Purpose: :
The evaluation of visual acuity (VA) in cognitively impaired older individuals may be limited by a reduced ability to cooperate or communicate. To date, no study has been performed to guide the clinician on which VA chart to use in older individuals with moderate to severe dementia. This is important knowing that dementia affects more than 30% of seniors above 85 yrs of age, many of whom will be affected by the most severe stages of the disease. The objective of this research was to assess VA in older individuals with moderate to severe dementia using various acuity charts and verify their ability to respond to each of these charts.
Methods: :
Three groups of 30 subjects each were recruited. The first group consisted of young subjects (Avg.±SD: 24.9±3.5yrs) and the second one, older subjects (70.0±4.5yrs) with no cognitive or communication disorders. The third group (85.6±6.9yrs) included subjects with moderate to severe dementia residing in long-term care facilities. The Mini Mental-State Examination (MMSE) was performed for each subject to verify their cognitive level. The VA of each participant was measured using six validated VA charts (Snellen, Teller cards, ETDRS-letters, -numbers, -Patty Pics, -Tumbling E's) presented in random order. Non-parametric tests were used to compare the VA scores between the various charts, after Bonferroni-Holm correction for multiple comparisons.
Results: :
The average MMSE scores of subjects with dementia was 9.8±7.5, while it was 17.8±3.7 and 5.2±4.6 respectively, for those with moderate (MMSE equal or above 13; n=11) and severe (MMSE below 13; n= 19) dementia. All subjects in groups 1 and 2 responded to each of the charts. A large proportion of subjects with dementia responded to all charts (n=19) while only one did not respond to any chart. In group 3, VA charts with the lowest scores were the Teller cards (20/65) and Patty Pics (20/62), regardless of the level of dementia, while the best VA scores were obtained with the Snellen (20/35) and ETDRS-letter (20/36) charts. More subjects with severe dementia responded to the Teller cards (n=18) but the VA obtained was the lowest (20/73). Across all groups, the ETDRS-letter chart was the only one whose scores did not differ from those obtained with the standard Snellen chart.
Conclusions: :
Visual acuity can be measured in older cognitively impaired individuals having a reduced ability to communicate. Our results indicate that the most universal scales, using letters as optotypes, can be used with good results in people with more severe dementia. Our results further suggest that the measurement of VA should to be attempted for all individuals, regardless of their cognitive level.
Keywords: aging • visual acuity • aging: visual performance