Abstract
Purpose :
Retinitis pigmentosa (RP) is a well-documented retinal degeneration. However, there have been few systematic reports of vision-related activity limitations of people with RP. We report an analysis of data from four studies that used the National Eye Institute Visual Function Questionnaire (NEI-VFQ).
Methods :
1,658 completed questionnaires were available from 492 individuals (aged 18 to 75 years) who participated in four studies at four institutions, with data for 208 participants over a period of four years with 109 of those providing data for five years. Rasch analysis was applied to 12 items of the Vision Function Scale (VFS: Pesudovs et al., 2010). Person scores were compared to the total point score for the combined 30-2 and 30/60-1 Humphrey Field Analyzer programs (HFA), 30-Hz electroretinogram (ERG) amplitude, and ETDRS visual acuity. Changes in person scores over time were examined. The mixed-effects models used account for repeated measures.
Results :
The Rasch model of the VFS responses had person separation of 2.2, person reliability of 0.83, item separation of 24.7 and item reliability of 1.00. The visual-functioning person scores were correlated with HFA (z=5.47, p<0.001), ERG amplitude (z=7.77, p<0.001), and visual acuity (z=10.6, p<0.001). Over the five-year period there was a reduction in average person scores of 0.1 logits p.a., from 2.4 to 1.9 logits (z=9.17, p<0.001).
Conclusions :
The NEI-VFQ VFS was found to provide a valid scale that was able to measure a reduction in perceived vision-related ability over a five-year period that was consistent with reductions in visual fields, ERG amplitude and VA.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.