Abstract
Purpose :
Age-related macular degeneration (AMD) is the leading cause of visual impairment in older adults and significantly impacts on activities of daily living, particularly under low light levels. Low light levels reduce postural stability in older adults generally, but have not been explored in those with AMD. This study investigated the effect of low light levels on postural stability in older adults with and without AMD.
Methods :
Participants included 31 older adults (17 controls and 14 AMD), aged 65 years and over. Postural stability was measured on a firm and foam surface with eyes open using an electronic force plate (Hurlabs) under 4 light levels: photopic (~436 lux, vertically at the eye), sudden reduction to mesopic (~436 to ~1 lux), adapted mesopic (~1 lux), and adapted mesopic with an LED door frame lighting system (~1.3 lux) in a random order. Vision measures included photopic and mesopic high contrast visual acuity (VA) and contrast sensitivity (CS; Pelli-Robson and Melbourne Edge Test), mesopic motion sensitivity, and binocular visual fields (VFs). The effect of light levels on postural sway parameters, including trace length (TL), anterior-posterior (AP) and medial-lateral (ML) sway, and associations between the vision function and sway measures were examined with linear mixed models.
Results :
Overall, light levels had a significant effect on TL (p<0.001) and AP (p=0.002), but not ML sway (p=0.68). Sway was greater in AMD compared to controls, particularly on the foam surface and under mesopic light levels. For both AMD and controls, the LED door frame significantly improved sway (TL, p=0.010; AP sway, p=0.041) on the foam surface under mesopic conditions. For the foam surface, motion sensitivity, photopic VA and CS and VFs were significantly associated with TL sway, all photopic and mesopic vision function were associated with ML sway, but only photopic CS was associated with AP sway.
Conclusions :
Decreased light levels significantly reduced postural stability in older adults with and without AMD, particularly on a foam surface. Various photopic and mesopic vision measures were associated with different aspects of sway on a foam surface. These findings have important implications for enhancing the visual environment for older adults with and without AMD to improve postural stability and reduce falls risk.
This is a 2020 ARVO Annual Meeting abstract.