Development and validation of a mobility test for Inherited Retinal Disease in real and virtual conditions - preliminary results.

Abstract

Purpose : Although Inherited Retinal Disease (IRD) are well characterized in terms of anatomical and functional progression, their impact on patients' daily lives is often poorly understood and lacks standardized measures as performance-based outcomes (PerfO) evaluating the performance in daily-life tasks, such as orientation and mobility. We developed a new mobility test in real (IRL) and virtual (VR) conditions and performed a prospective, interventional non-invasive, longitudinal study (test-retest) to compare the performance of IRD patients and healthy participants in both conditions (IRL v.s. VR).

Methods : Fifteen retinitis pigmentosa patients and 15 age-matched healthy participants had to walk through a maze either physically presented (IRL) or displayed in a virtual reality headset (HTC Vive Pro Eye). In multiple light level conditions (between 1 Lux and 400 Lux in IRL), participants were instructed to step over two steps, pass under two flags, avoid a cone and two high obstacles, avoid a dead-end, and finally reach an end goal. Trial duration and errors were automatically recorded in VR condition. In IRL condition, errors were live coded by an experimenter and recorded by a different experimenter after the session. We computed a performance score taking in account duration and errors.

Results : Preliminary results indicate a good construct validity (discrimination between groups, ROC area>.9), a very good agreement of the performance score between sessions (ICC>.95) and between VR and IRL conditions (ICC>.9), and a good content validity (correlation with a visual score .41 and .65). Moreover, test duration was acceptable for 95% of participants (both conditions) and the VR experience was rated as enjoyable for 73% of participants. 78% of RP participants felt that the VR test was representative of their difficulties in daily life.

Conclusions : We have designed a locomotion test, both in real (IRL) and virtual (VR) conditions, that has excellent reproducibility and high agreement between both conditions. Additional data are awaited to confirm these results, and measure sensitivity to change which will determine its interest in monitoring the progression of a retinal disease and assessing the efficacy of new treatments.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.