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Claire S Barnes; Testing novel scales for the NEI Visual Function Questionnaire (VFQ) in age-related macular degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2018;59(9):3408. doi: https://doi.org/.
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Issues with the NEI VFQ, such as multidimensionality, led Marella et al., Pesudovs et al. and others to derive Visual Functioning (VF) and Socioemotional (SE) scales, in place of the standard VFQ composite score and subscales. The utility of the new scales has not been examined specifically in AMD yet, so in this study, data from individuals with AMD were compared for the new scales and standard subscales.
45 subjects tested (ages 63 — 94 years; 69% males). Vision measures: monocular and binocular visual acuity (VA) with ETDRS charts; binocular contrast sensitivity (CS) with Pelli-Robson charts; binocular maximum reading rate (MRR) and critical print size (CPS) with MNRead charts. The VFQ-25 was administered by experienced interviewers. Items for the VF and SE scales were those used in Pesudovs et al. (2010). Internal consistency and validity measures were examined.
Median (range) binocular VA was 0.20 logMAR (1.38 to -0.16); log CS was 1.50 (0.15 to 1.95); MRR was 150 words/min (6.5 to 220); and CPS was 0.5 logMAR (0.1 to 1.3). Subject ages did not correlate with the vision measures, and showed little or no correlation with the scales or subscales (p-values ≥ 0.06, except for Mental Health, Dependency and Driving (p-values ≥ 0.04)). The p-values were <0.0001 for all correlations of the vision measures with the VF and SE scales, and with most of the subscales other than General Health and Ocular Pain. Cronbach’s α was ≥ 0.7 for all subscales except Social Function and Driving, and each VFQ item correlated more closely with its own subscale (r ≥ 0.57) than with any other subscale. Cronbach’s α was > 0.9 for the VF and SE scales, and each item except #11 correlated more closely with its own scale (VF or SE, r ≥ 0.57) than the other. The number of extreme scores (0 or 100) was generally lower for the VF and SE scales than for the subscales.
In this AMD study, the correlations between most VFQ scales and subscales were strong. Correlations with the vision measures were generally highest for the Near Activities subscale, followed by the VF scale. These results support the use of the VF and SE scales for VFQ analysis in AMD, but the overall results were too similar to judge the new scales as superior to the standard subscales. Interestingly, the correlations of many (sub-)scales were stronger for the worse-eye VA than for the better-eye or binocular VA.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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