Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa

Latham, Keziah, Baranian, Mohammad Ahoora, Timmis, Matthew A., Fisher, Andy and Pardhan, Shahina (2017) Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa. Optometry and Vision Science, 94 (3). pp. 317-328. ISSN 1538-9235

Accepted Version
Available under the following license: Creative Commons Attribution Non-commercial No Derivatives.

Download (387kB) | Preview
Official URL:


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.

Item Type: Journal Article
Keywords: retinitis pigmentosa, activities of daily living, rehabilitation, visual impairment, Rasch analysis, orientation and mobility, mobility aids
Faculty: ARCHIVED Faculty of Science & Technology (until September 2018)
Depositing User: Keziah Latham
Date Deposited: 13 Mar 2017 16:40
Last Modified: 09 Sep 2021 18:59

Actions (login required)

Edit Item Edit Item