Objective: Designing clinical trials for advanced retinal disease represents an especially difficult challenge due to the lack of suitable outcome measures. Clinical measures such as visual field and area of atrophy measured with multimodal imaging may be highly variable and/or difficult to measure in this population. A main contributor to disability in the visually impaired is poor mobility, which is a quality of life measure used to assess visually-guided behavior in low-vision patients. The goal of our study is to determine whether parameters from a recently developed virtual reality (VR) mobility assessment tool may serve as biomarkers of functional vision in participants with advanced retinal disease. The long-term goal will be to determine whether the VR mobility assessment tool parameters can document longitudinal changes in functional vision and serve as a suitable outcome measure for clinical trials in participants with advanced retinal disease.

Study Population: Up to 120 participants with retinal disease and 45 healthy volunteers will be recruited. The upper limit of 120 participants with retinal disease was chosen to allow approximately equal groups of 60 participants with rod-cone degeneration (RCD) and 60 participants with cone-rod degeneration (CRD) to represent groups of participants with peripheral visual field constriction and central vision loss, respectively. A total of 60 per group was chosen to A) allow feasibility to be determined across age groups (e.g., 5-11 yrs., 12-50 years, over 50 years) and B) to allow for a sufficient range of disease severity to examine VR mobility test sensitivity. The number of healthy volunteers (N=45) was chosen to provide about 15 participants across each of three age groups.

Design: In this multi-site observational study, VR mobility testing will be performed in participants with retinal disease. While the ultimate goal is to use this for advanced retinal disease, in the current study we will examine patients with a wide range of retinal disease severity to enable correlations between VR mobility parameters and markers of disease severity (e.g. field size, mobility scores from questionnaires). This analysis will also help determine the range of retinal disease severity for which VR mobility will be useful. Testing will also include best corrected visual acuity (BCVA), visual fields, optical coherence tomography (OCT), autofluorescence imaging, ultra-widefield imaging and participant reported outcome (PRO) questionnaires. Based on the simulation studies, we predict that participants should be able to repeat the VR course between four to eight times in a one-hour session. Participants will be required to attend up to two clinic visits within three months. VR testing will be the focus of the second clinic visit in order to A) examine the learning effect and B) quantify test-retest variability of VR test parameters.

Outcome Measures: The primary outcome is to determine whether parameters from a recently developed VR mobility tool can serve as biomarkers of functional vision in participants with retinal disease. To this end, we will examine the correlation between VR mobility test parameters (e.g., accuracy, task time) and clinical measures of retinal structure and function (e.g., visual acuity, non-seeing area) and the mobility score from a PRO questionnaire/s. Other primary outcomes include quantifying the learning effect and test-retest variability of the VR test parameters. A secondary outcome is to examine whether prior or present computer game playing (e.g., number of hours, type of games played, computer game platform) influences baseline performance on the VR mobility tool.