Mobility of People with Retinitis Pigmentosa as a Function of Vision and Psychological Variables

Haymes, Sharon A.; Guest, Daryl; Heyes, A. D.; Johnston, Alan

doi:10.1097/00006324-199610000-00001

Cited by 128 publications

(135 citation statements)

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“…The most difficult items overall, those around poor light and obstacle avoidance 326 (subscale 4), are even more difficult for those in the earlier stages of the condition, namely those 327 who are younger, who do not use mobility aids, and who are either not registered or registered only 328 as sight impaired. Since mobility difficulties tend to increase as the extent of visual field loss 329 increases, 7,26,33 it might have been expected that mobility tasks such as avoiding peripheral 330 obstacles would have been more difficult for those in the later stages of the condition, who are more 331 likely to be registered as severely sight impaired. However, it could also be argued that as the 332 disease progresses, adjustments to approaches to mobility are made from an early stage, such that 333 these tasks seem less of an issue than they do earlier in the disease process, and newer difficulties, 334 such as those with visual search as the field contracts to very small levels, are relatively more 335 difficult as they need to become adapted to.…”

Section: Differential Item Functioning 228mentioning

confidence: 99%

Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa

Latham¹,

Baranian

Timmis³

et al. 2017

Optom Vis Sci

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Purpose To determine the relative difficulty of activity of daily living tasks for people with retinitis pigmentosa (RP). Methods Participants with RP (n = 166) rated the difficulty of tasks (n = 43) underpinning the Dutch Activity Inventory goals of mobility indoors and outdoors, shopping, and using public transport. Demographic characteristics were also determined. Responses were Rasch analyzed to determine properties of the scale, derive unidimensional subscales, and consider differential item functioning (DIF). Results After removal of one ill-fitting item, the remaining 42 tasks formed a scale with reasonable Rasch parameters but poor unidimensionality. The most difficult tasks were orienting in poor and bright light both indoors and outdoors, and avoiding peripheral obstacles outdoors. Eight subscales were derived with unidimensional properties, each of which could be considered as requiring similar skills. DIF identified that tasks from the “poor light and obstacles” subscale were more difficult for those younger than the median age, nonusers of mobility aids, and those not registered or registered sight impaired. Tasks from the “finding products” and “public transport” subscales were more difficult for those older than the median age, with longer duration of visual loss, users of mobility aids, and those registered severely sight impaired. Conclusions The most difficult tasks for people with RP of orienting in poor light and avoiding peripheral obstacles are relatively more difficult for those not registered as “severely sight impaired,” but are less difficult for those who use mobility aids. Mobility aids (guide dog or cane), therefore, do benefit users in their perceived ability in these particular tasks. The derived unidimensional subscales reorganize the tasks from those grouped together by goal (researcher driven) to those perceived as requiring similar skills by people with RP (patient driven) and can be used as an evidence base for orientation and mobility training protocols.

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Section: Differential Item Functioning 228mentioning

confidence: 99%

Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa

Latham¹,

Baranian

Timmis³

et al. 2017

Optom Vis Sci

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“…It has been well documented that the spatial abilities of patients who have lost a portion of their visual field are generally impaired (Fortenbaugh et al, 2008;Haymes, Guest, Heyes, & Johnston, 1996;Marron & Bailey, 1982;Szlyk et al, 1997;Turano, Geruschat, & Stahl, 1998). It has also been reported, however, that there are large individual differences among these patients in their spatial competence, demonstrating that while some patients suffer from substantial impairment, others can perform spatial tasks as well as normally sighted observers (Turano, 1991;Turano & Schuchard, 1991).…”

Section: Discussionmentioning

confidence: 99%

Peripheral vision benefits spatial learning by guiding eye movements

Yamamoto

Philbeck

2012

Mem Cogn

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The loss of peripheral vision impairs spatial learning and navigation. However, the mechanisms underlying these impairments remain poorly understood. One advantage of having peripheral vision is that objects in an environment are easily detected and readily foveated via eye movements. The present study examined this potential benefit of peripheral vision by investigating whether competent performance in spatial learning requires effective eye movements. In Experiment 1, participants learned room-sized spatial layouts with or without restriction on direct eye movements to objects. Eye movements were restricted by having participants view the objects through small apertures in front of their eyes. Results showed that impeding effective eye movements made subsequent retrieval of spatial memory slower and less accurate. The small apertures also occluded much of the environmental surroundings, but the importance of this kind of occlusion was ruled out in Experiment 2 by showing that participants exhibited intact learning of the same spatial layouts when luminescent objects were viewed in an otherwise dark room. Together, these findings suggest that one of the roles of peripheral vision in spatial learning is to guide eye movements, highlighting the importance of spatial information derived from eye movements for learning environmental layouts.

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“…Therefore, it would be intuitive to reason that visual function and mobility performance is substantially correlated, and many researchers have shown this relationship (Geruschat, Turano, & Stahl, 1998;Haymes, Guest, Heyes, & Johnston, 1996;Kuyk, Elliott, & Fuhr, 1998a;Marron & Bailey, 1982). These studies have shown that clinical measures, such as visual acuity, contrast sensitivity, and visual field are predictive measures to mobility performance.…”

Section: Scanning Abilitymentioning

confidence: 99%

“…In performance evaluations of reading at matched luminance levels, Kleweno et al (1999) reported that 3 out of 13 subjects showed a clinically significant increase in reading speed, and 6 out of 13 showed increased visual acuity when using the VRD versus a CRT. Since visual acuity has been shown to be significantly correlated with mobility performance (Geruschat, Turano, et al, 1998;Haymes et al, 1996), a wearable form of the VRD (WVRD) is expected to increase the mobility performance of some low vision individuals. Unlike conventional HMDs, the higher illuminance and contrast levels due to the scanning laser light will allow the low vision aids to be used effectively in bright outdoor environments and in augmented (see-through) modes of display.…”

Section: The Vrd and Low Visionmentioning

confidence: 99%

Testing Visual Search Performance Using Retinal Light Scanning as a Future Wearable Low Vision Aid

Lin¹,

Seibel²,

Furness³

2003

International Journal of Human-Computer Interaction

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For the goal of designing a wearable low vision aid, aspects of both head-mounted display (HMD) design and performance evaluation were integrated into a single study of scanning ability. A head-mounted version of a novel retinal light scanning display known as the virtual retinal display was fabricated for this study. A remote head CCD (charge coupled device) attached approximately at the user's line of sight was used as the input source. Scanning ability was quantified as the time to identify a target in a wide field of distractors while using the HMD design in four different display interface modes (DIMs). Each DIM was tested with respect to their corresponding controls: A (augmented, see-through) and CO (center occluded) DIMs were compared to the augmented control (augmented, retinal display turned off), and CPO (center and periphery occluded) and PO (periphery occluded) DIMs were compared to the periphery occluded control (periphery obstructed, retinal display turned off). Each DIM was tested at high, medium, and low contrast levels. Five subjects were tested without optical correction (visual acuity worse than 20/200), which accurately represented low vision subjects. Results showed that for each DIM, scanning performance decreased as the contrast level decreased. At the INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION, 15(2), 245-263 Copyright © 2003, Lawrence Erlbaum Associates, Inc.We thank Nick Kipping (student in Industrial Design) and Robert Burstein (Research Engineer) for their technical assistance, Duff Hendrickson (Experience Designer) for the computer animations, The National Science Foundation for funding this research (Grants 9801294 & 9978888), the R.E.U. program, and The Mary Gates Foundation for financial assistance.Sun-Kai V. Lin is now at the Department of Bioengineering, University of Pennsylvania. Requests for reprints should be sent to Sun-Kai V. Lin, Department of Bioengineering, University of Pennsylvania, 120 Hayden Hall, 3320 Smith Walk, Philadelphia, PA 19146. E-mail: sklin@ seas.upenn.edu lowest contrast level, the PO DIM provided the greatest and most significant improvement in scanning performance. At the medium and highest contrast levels, all DIMs provided equal or worse performance than their controls. Additionally, the subjects' natural visual acuity showed no correlation with scan time. All subjects reported a higher acuity with the retinal display, and showed a diverse range of preference for the most helpful DIM. Based on these results, we realized that low vision applications have unique design requirements unlike those for normally sighted users, and therefore customization of a wearable low vision aid may be an optimal design strategy.

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Mobility of People with Retinitis Pigmentosa as a Function of Vision and Psychological Variables

Cited by 128 publications

References 0 publications

Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa

Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa

Peripheral vision benefits spatial learning by guiding eye movements

Testing Visual Search Performance Using Retinal Light Scanning as a Future Wearable Low Vision Aid

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