@article {1517198,
	title = {Validation of a vision-related activity scale for patients with retinitis pigmentosa},
	journal = {Health Qual Life Outcomes},
	volume = {18},
	number = {1},
	year = {2020},
	month = {2020 Jun 22},
	pages = {196},
	abstract = {PURPOSE: There have been few systematic reports of vision-related activity limitations of people with retinitis pigmentosa (RP). We report a merging of data from the National Eye Institute Visual Function Questionnaire (NEI-VFQ) obtained in five previous studies. We asked whether the Vision Function Scale (VFS; Pesudovs et al., 2010) which was developed for cataract patients would apply in this new population (condition). METHODS: Five hundred ninety-four individuals completed a total of 1753 questionnaires, with 209 participants providing responses over at least 4 years. Rasch analysis showed that the 15-item VFS was poorly targeted. A new instrument created by adding four driving-related items to the VFS had better targeting. As an indirect validation, VFS-plus person scores were compared to visual field area measured using a Goldmann perimeter, to the summed score for the combined 30-2 and 30/60-1 Humphrey Field Analyzer programs (HFA), to 30-Hz full-field cone electroretinogram (ERG) amplitude, and to ETDRS visual acuity. Changes in VFS-plus person scores with age and between four common heredity groups were also examined. RESULTS: The Rasch model of responses to the 19 VFS-plus items had person and item separation of 2.66 and 24.43 respectively. The VFS-plus person scores were related to each vision measure (p \&lt; 0.001). Over a five-year period, there was a reduction in person scores of 0.5 logits (p \&lt; 0.001). Person scores fell by an average of 0.34 logits per decade (p \&lt; 0.0001). Participants with an X-linked hereditary pattern had, on average, lower person scores (p \&lt; 0.001). CONCLUSIONS: The VFS-plus instrument quantified a highly-significant annual reduction in perceived vision-related ability over a five-year period. The outcome was consistent with clinical measures of vision, and detected lower perceived vision-related ability in participants with X-linked disease. It may be of use in future studies, but this needs to be tested in a representative population sample.},
	issn = {1477-7525},
	doi = {10.1186/s12955-020-01427-8},
	author = {Costela, Francisco M and Pesudovs, Konrad and Sandberg, Michael A and Weigel-DiFranco, Carol and Woods, Russell L}
}
