Validation of a quality of life measure (VIQoL) for adults living with vision impairment

Abstract

Quality of life (QoL) measures are often used to assess the effectiveness of services and interventions. For individuals living with vision impairment (VI) this is potentially problematic, given that QoL is characteristically assessed using instruments designed with non-VI norms and may not accurately represent issues specifically associated with VI. Hence, the authors designed an instrument (Vision Impaired Quality of Life [VIQoL]) tailored for adults living with VI. This article reports on VIQoL’s psychometric properties and outlines its utility for the VI sector. Principal Axis Factoring (PAF) was used to assess VIQoL’s construct validity, conducted on a combined dataset of adults with VI ( n = 582), and adults without VI ( n = 1992). To assess factor integrity, analyses were conducted on these groups separately. Reliability was assessed using Cronbach’s alpha. VIQoL display high construct validity and reliability. PAF analysis presented a two-factor solution: ‘functional confidence’ (items encompassing autonomy and frequent demands of life), and ‘personal flourishing’ (items related to affect and feeling). VIQoL is a valid and reliable tool for assessing QoL for people living with VI. It affords a basis for meaningful evaluations and insights into how differences in QoL are appraised by VI and non-VI populations; although factors were fundamentally similar, the importance of the two factors was reversed across the groups, which highlights the importance of condition-specific QoL measures and implies the need for research to assess other variables that can affect the QoL of people living with VI.