Abstract
Purpose :
A comparative clinical trial was conducted to evaluate the effectiveness of a virtual bioptic telescope in an HMD vision enhancement system possessing a wide field of view to currently employed specifications in HMD vision enhancement technology through patient reported outcome measures. As HMDs are being developed and implemented into clinical vision rehabilitation, it is important to evaluate the effectiveness of new features as it translates into the functional ability of visually impaired individuals.
Methods :
Patients were randomized into two arms with the following HMD specifications: 1. a magnification bubble embedded in an unmagnified 70° field of view (bubble) and 2. full-screen magnification in a 45° field of view (legacy). Participants completed baseline testing then took the device home for a 2-4 week trial period. Participants were encouraged to use the device in their daily activities (excluding mobility). The Activity Inventory (AI) was administered before and after the home trial to measure the effect of system use on self-reported functional ability measures. Baseline and follow-up AI results were analyzed using Rasch analysis.
Results :
A total of 88 (n=44 legacy, n=44 bubble) participants with BCVA of <20/60 in the better-seeing eye and at least 70° of peripheral visual field completed the study. There was no difference in age, BCVA, or baseline AI person measures between groups. In the legacy group, improvements were seen in reading (Cohen’s d=0.99, p <0.001) and inside-the-home tasks (d=0.44, p=0.04). In the bubble group, improvements were seen in reading (d=0.82, p <0.001) and visual information tasks (d=0.39, p=0.03). There was no improvement in visual motor function or mobility in either group. Between group effects did not reach statistical significance.
Conclusions :
Based on the AI results, use of both the legacy and bubble HMD result in improvements in reading, visual information (i.e. seeing faces), and inside-the-home tasks with reading having the strongest effect size. The lack of improvement in mobility and visual motor function is expected and likely due to limited field of view and lack of binocular disparity. There were trends for legacy device users to report better outcomes with reading and in-home tasks and bubble users to report better outcomes with visual information tasks, but there was no significant difference between groups.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.