Falls have a major impact on the quality of life of fallers and on the health and social economy of the nation. An evidence base of predominantly laboratory studies exists, which suggests bifocal and progressive addition lens designs increase falls risk. Findings either lacked discrimination between bifocal and progressive addition lenses, were not powered to differentiate between them, or were based on the premise that gaze direction when walking or using stairs is through the lower, near powered zones. This has led to single vision lenses being recommended to those at falls risk. The primary aim of the studies described in this thesis was, therefore, to investigate whether field trials in the form of a retrospective case control and a prospective cohort study of community-dwelling elderly persons supported previous recommendations. A survey of GOC registered optometrists and dispensing opticians was undertaken before the main study. Single vision lenses were the lens design of choice for patients deemed at risk of falls.The main study uniquely differentiated between single vision, bifocal and progressive addition lenses in a UK-based population study of well habituated wearers. A measure of visual attention (Global Measure of Vision) was designed and evaluated specifically for the study. Established “Timed up and Go” and SF12v2 provided measures of participants’ balance, mobility, and physical and emotional wellbeing. Logistic regression analysis showed no variable demonstrated statistically significant influence on falls risk in the retrospective study, including spectacle lens design. In the prospective study, previous fall history was the only significant predictor of falls (Odds Ratio: 2.71, p = .01), aligning with levels reported in a recent meta-analysis. This study did not confirm that bifocal or progressive addition lens wear increases falls risk in well-habituated community-dwelling older people, and indicates that changing to single vision lenses may not be necessary.
|Date of Award||20 Nov 2017|
|Supervisor||Mark Dunne (Supervisor)|
- single vision
- progressive addition lens