Benefit of an electronic head-mounted low vision aid.

Abstract

To evaluate the efficacy of electronic head-mounted low vision aid (e-LVA) SightPlus (GiveVision, UK, givevision.net) and to determine which people with low vision would see themselves likely using an e-LVA like this. Sixty participants with low vision aged 18 to 93 used SightPlus during an in-clinic study session based ona mixed methods design. Visual acuity (ETDRS), contrast sensitivity (Pelli-Robson) and reading performance (MNREAD) were measured binocularly at baseline (no device), with the device in 'normal' mode (zoom only), and with preferred enhanced mode (zoom and oneof four digital image enhancements). At the end of the session, a short questionnaire recorded willingness to use an e-LVA like SightPlus, potential use cases, positive/negative comments and adverse effects. Binocular distance visual acuity improved significantly by 0.63 logMAR on average (p<0.0001) to 0.20 logMAR. Contrast sensitivity improved significantly by 0.22 log units (p<0.0001) to 1.21 log units with zoom only and by 0.40 log units to 1.37 log units with zoom and preferred image enhancement. Reading performance improved significantly for near visual acuity and critical print size (p<0.015), although reading speed significantly decreased (p<0.0001). Nearly half (47%) of the participants indicated they would use an e-LVA like SightPlus, especially for television, reading and entertainment (e.g. theatre). Multivariate logistic regression showed that proportion of lifetime affectedby sight loss, baseline contrast sensitivity and use of electronic LVAs explained 41% of the variation in willingness to use. SightPlus improves visual function in people with low vision and would be used in its current form by one half of the people who tried it. Adverse effects were infrequentand resolved when the device was removed. Future work should focus on comparing e-LVAs through repeatable real-world tasks and impact on quality of life.