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Amy Scarfe, Matthew Timmis, Rupert R A Bourne, Shahina Pardhan; Step ascent performance in patients with central and peripheral vision loss.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4770.
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© ARVO (1962-2015); The Authors (2016-present)
To compare step ascent performance between patients with central vision loss (due to AMD), peripheral vision loss (due to glaucoma) and in normally sighted age-matched controls.
Three-dimensional motion data were collected from 10 AMD (age: 73±9 years; LogMAR VA: 0.74±0.42), 10 glaucoma (age: 71±9 years; LogMAR VA: 0.18±0.17) and 10 control participants (age: 71±5 years; LogMAR VA: 0.01±0.08), as they walked up to and ascended a single step of three varying heights (low = 8.5cm; medium = 16cm; high = 23.5cm). Movement of the lead and trail limbs were analysed. LogMAR visual acuity (VA), contrast sensitivity (CS), stereopsis and visual fields (VF) were measured.
In comparison to glaucoma and control groups, AMD patients moved their lead foot significantly slower as it crossed the apex of the step (glaucoma p=0.028; controls p=0.016). AMD patients also spent longer with both feet in contact with the ground prior to initiating the step up (double support) compared to glaucoma patients (p=0.014) and controls (p=0.008). Trends towards decreased gait velocity at key points in the task (when the lead and trail foot leave the ground prior to the step up, and also when they contact the step), indicate that AMD patients’ movements were slower than both glaucoma patients and controls (p<0.071). Step height had a significant main effect on a number of movement indices, indicating that all groups modified their movements in the same manner as task difficulty increased (p<0.05).<br /> Movement indices were significantly correlated with visual acuity, contrast sensitivity and binocular visual field defects averaged across central 5˚, 10˚, 20˚ and 20˚-30˚ (p<0.05).
AMD patients demonstrated a more cautious gait strategy compared to both glaucoma patients and controls. Previous research suggests that such a strategy is used in order to minimise the risk of falling and injury should a trip occur. These findings highlight the importance of adequate central vision when performing a step ascent. Participants with more severe vision loss show greater changes in their mobility.
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