Andrew Freedman¹, Preeti Verghese¹; ¹Smith-Kettlewell Eye Research Institute

Individuals with macular degeneration (MD) must rely on peripheral vision, where contrast sensitivity is lower. Greater target contrast improves search performance in an on-screen search task, but it is unclear if this holds for naturalistic search while walking in a virtual reality (VR) environment. To investigate this, we measured search performance in a VR space for participants with MD (n=2) and controls with a 10° gaze-contingent artificial scotoma (n=9). Furthermore, we investigated whether the presence of a salient black-and-white striped border would improve performance regardless of target contrast. The task was to find a generic cylindrical target among similar distractors, distributed throughout a realistic scene. Participants saw a preview of the target object, then walked through the room and indicated when they detected the target object. Target contrast and the presence of the visibility enhancement were randomized across trials. Results show differential benefits from high target contrast and the visibility enhancement between the MD and control groups. Controls with the artificial scotoma performed better on average than MD participants, detecting targets faster and with higher accuracy, and did not benefit from the visibility pattern. The visibility pattern improved search efficiency for MD participants, reducing search time by 2.8 seconds, F(1, 1) = 192.746, p = 0.045. High-contrast targets significantly improved search performance for controls with the artificial scotoma, who detected those targets 5.6% more frequently, F(1, 8) = 5.97, p = 0.04, and 0.6 seconds faster, F(1, 8) = 5.522, p = 0.047, while MD participants saw no benefit. Thus, preliminary data suggest that high contrast, either from a target itself or an enhanced boundary, can improve search performance, but the benefit may depend on the nature and severity of the observer’s central field loss.

Acknowledgements: This work was supported by the NIH grants T32EY025201 and R01EY027390.