Purchase this article with an account.
Tiana M. Bochsler, Gordon E. Legge, Rachel Gage, Christopher S. Kallie; Does Locomotion Enhance the Visibility of Ramps and Steps for People with Low Vision?. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4355.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Accurate detection of ramps and steps is an important aspect of mobility for people with low vision. The present study extends previous findings from our lab on the recognition of ramps and steps by stationary subjects (Legge et al., J. Vis., 2010; Bochsler et al., ARVO, 2010). Cues arising from locomotion can provide information about surface depth and orientation. The current investigation explores whether locomotion toward a ramp or step enhances recognition accuracy in subjects with low vision.
Sixteen low vision subjects participated-aged 33 to 65-with heterogeneous diagnoses, and acuity from 20/120 to 20/960. They viewed a sidewalk located in an indoor, windowless classroom. It was interrupted by one of five possible targets: a single step up or down, a ramp up or down, or flat. In a block of trials, subjects reported which of the five targets was shown, and percent correct was computed. They made target recognition judgments from a distance of 10ft either after stationary viewing or after walking from 20ft to the same viewing location. Performance was compared with a group of normally sighted subjects who viewed the targets monocularly through goggles with two levels of blur having effective acuities roughly spanning the low-vision range (20/135 and 20/900).
Both low vision subjects and goggle-wearing subjects with normal vision recognized ramps and steps significantly more accurately in locomotion trials (81% correct) than in stationary trials (69% correct), p < .02. Consistent with our previously reported findings on a variety of conditions with stationary viewing, the majority of our low-vision subjects (11 out of 16) outperformed acuity-matched performance levels of the goggle wearers (p < .01). The order of target performance from best to worst was similar for the stationary and locomotion conditions. In both conditions, subjects performed best on the same three targets, in the following order: step up, step down, ramp up.
Locomotion through an environment may increase the visibility of obstacles for people with low vision. This motion-dependent improvement may be due to motion parallax, accretion/deletion of surface features, or enhancement of the visibility of informative contours by retinal image motion.
This PDF is available to Subscribers Only