Advisory Committee Chair
Mark Swanson
Advisory Committee Members
Roderick Fullard
Lei Liu
Document Type
Thesis
Date of Award
2017
Degree Name by School
Master of Science (MS) School of Optometry
Abstract
ABSTRACT Purpose: Previous studies have shown that there is an association between visual acuity and Alzheimers’ disease. Untreated visual problems may contribute to cognitive impairment and more progressive cognitive decline. This study investigates the association of chart design, specifically comparing charts using letters versus numbers, to accuracy and repeatability among patients with dementia. Methods: 23 English-speaking subjects diagnosed with moderate to advanced levels of dementia were recruited from two local Birmingham nursing homes. Visual acuities were measured in a randomly selected eye and timed from six different charts: Back-illuminated ETDRS chart with letters, Back-illuminated ETDRS chart with numbers, HOTV cards with single, isolated letters, Lea cards with numbers, HOTV cards with single crowded letters, Lea cards with single crowded numbers. Acuities were re-measured and timed using the same subjects and same charts in random order, one week later. Non-parametric tests were used to evaluate differences between measured chart acuities. Intra class correlation coefficients between administrations were calculated using a linear mixed model. Results: The best acuities were achieved with single letter (20/25 median) and single number charts (20/25 median). The poorest acuity was achieved with both the ETDRS number (20/50) and letter charts(20/50). Differences between ETDRS number and letters acuities were poorer (p<0.005) than comparable single letter acuities and between crowded versus uncrowded single iv letter (p<0.05). Best agreement between first and second acuities on the same chart was with inserta section single letter acuity with intraclass correlation coefficient of 0.79, followed by ETDRS letter ICC 0.55 and single number 0.55. Conclusion: Single letter charts provided the best and most repeatable acuity among this group of subjects with dementia. There appears to be no number or letter bias for better acuity among this group. The worsening acuity with increasing chart complexity suggests a crowding effect or global distraction factor with chart type.
Recommended Citation
Berry, Sarah, "A Comparison Between Number And Letter Acuities Among Patients" (2017). All ETDs from UAB. 1152.
https://digitalcommons.library.uab.edu/etd-collection/1152