Usability of Augmented Reality Head Mounted Displays (AR HMD) for Reading Studies

BACKGROUND: Reading is a cognitively challenging skill that is used frequently in daily life, involving various visual factors. Previous studies have shown the impact of visual impairments on reading. The implementation of augmented reality (AR) is relatively new in ophthalmology. Studies have applied AR Head Mounted Displays (HMD) in vision enhancing systems for older drivers or as an instrument to compensate for metamorphopsia; however, the usability of an AR-HMD in ophthalmologic research has received little attention. The aim of this study was to assess the usability of AR-HMD for reading studies.

PATIENTS AND METHODS: Participants were randomly assigned to read aloud four of five texts with a similar level of reading skill as fast and accurately as possible, as displayed either on a PC monitor or on the Varjo XR4 AR HMD. Each test consisted of two reading blocks: a pilot for the participant to get familiar with the setup and the test with the recorded reading performance (4 blocks, 2 × 2). Reading speed (words/min) were recorded in both displays and eye movements were tracked for the reading experiment in the PC. At the end of the study, participants were asked about comfort, the adjustment of the AR-HMD and challenges experienced during the experiment.

RESULTS: All participants (n = 31) successfully completed all blocks. There was no significant difference in the speed at which participants read the pilot and test reading texts in either device; however, there was a significant difference between the reading speeds assessed with the PC and with the AR HMD (p = 0.003). The average saccade amplitude and average peak velocity were strongly correlated. Individual mean saccade amplitudes ranged from 1.47° to 1.65° and the mean of the mean fixation durations were calculated at 276 - 288 ms. Common complaints with the AR HMD included its weight and tightness and some participants reported an unnatural visual experience during use.

CONCLUSIONS: This study demonstrated the potential usability of an AR HMD device for reading experiments. Future uses of AR-HMD could leverage its advanced technical capabilities (eye and head tracking) for complex visual behavioral studies, realistic simulation of ophthalmic diseases, and objective assessment of driving capability in real-world scenarios.