Abstract
Purpose :
To study possible effects of age, duration of eye condition, visual function, and rehabilitation history on self-reported visual ability in a population with ultra-low vision (ULV), using the 150-item Ultra-Low Vision Visual Functioning Questionnaire (ULV-VFQ) (Jeter, TVST 6:11, 2017).
Methods :
In an on-going recruitment effort, 45 individuals aged 24 – 97 (mean 56) with ULV due to a wide range of congenital and acquired conditions have been recruited at The Chicago Lighthouse. The ULV-VFQ was administered to participants over the phone or online, querying them on the difficulty of performing everyday visual tasks, such as locating their silverware on the dinner table or seeing a towel on a rack. Person measures were calculated using Winsteps© with anchored items and response structure, and correlated with demographic variables: age, duration of vision loss, visual acuity (VA, logMAR, with hand motions coded as 3.0, light perception as 4.0), and devices used (as a surrogate for visual performance; 0: none or unknown; 1: non-visual, e.g., tactile & auditory; 2: opto-electronic; 3: optical).
Results :
Eighteen subjects had VA in the better eye of HM or LP; mean±SD VA was 2.5±0.8 logMAR; 21 did not use visual aids. The person measure distribution of the CLH cohort ranged from -3.17 (less ability) to +6.23 (more ability), with a mean of +0.86. Person measures were significantly correlated with age (r=0.32) and VA (r=0.77), and associated with device use classification (r=-0.42), but not duration of vision loss. The correlation between VA and age was low (0.16). One can assume, therefore, that in this ULV population VA accounts for 80% of the variance in person measure, and age for up to 10%.
Conclusions :
Our results show that ~60% of variance in the person measures can be attributed to VA expressed as logMAR equivalents. Studies using VFQs in low vision populations with mild to severe visual impairment have found similar correlation levels. These findings show that self-reported visual ability assessment in individuals with profound vision loss has strong face validity, and that use of the ULV-VFQ is a logical extension of VFQs in less impaired populations.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.