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Rob Chun, Robert W Massof; Characterizing differences in functional ability between RP low vision patients and non-RP low vision patients. Invest. Ophthalmol. Vis. Sci. 2020;61(7):938.
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© ARVO (1962-2015); The Authors (2016-present)
Prior work has examined how visual impairments affect various aspects of daily function in the general low vision (LV) population through visual function questionnaires. Visual impairment associated with Retinitis Pigmentosa (RP) is unique from most other LV conditions as central vision is often spared until advanced stages. Thus, we performed a retrospective, observational study to examine differences in functional deficits between RP LV patients and non-RP LV patients.
Data from a previous IRB-approved prospective study of 2066 LV patients 18 years or older were compiled. There were no visual impairment criteria excluding patients from participating in this prior study. Rasch analysis was employed to determine functional ability estimates (person-measures) from patient reported difficulty ratings on the psychometrically validated visual function questionnaire known as the Activity Inventory (AI). The AI contains 510 survey items covering a broad range of tasks that define overall functional ability, in addition to 4 functional domain categories (Reading, Mobility, Visual Information, and Visual Motor). We segregated 66 RP patients from the cohort using ICD-9 diagnosis codes to compare cumulative frequencies of person-measures for overall functional ability and each functional domain. Two-tailed t-tests and F-tests were used to compare distributions of the two groups (RP LV vs non-RP LV).
Larger person measures indicated greater ability. The RP LV group (red curve) had significantly greater reading (t-test p =0.04) and visual motor (t-test p=0.01) ability than the non-RP LV group (black curve). No significant differences were seen in overall functional ability (AI Goals, t-test p=0.75, F-test p=0.53) or visual information (t-test p=0.63, F-test p=0.72) categories. Differences in mobility function appeared to approach significance when comparing the variance of the two groups (F-test p= 0.08), but the means of the distributions were not significantly different from each other (t-test p=0.51).
Visual impairments associated with RP are distinct from other LV conditions and cause different functional impairments on average. Because central vision is typically spared until late in the disease, RP LV patients report better reading and visual motor abilities than non-RP LV patients. However, mobility function appears to behave differently in RP LV patients.
This is a 2020 ARVO Annual Meeting abstract.
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