Efficacy of a wearable night-vision aid in patients with concentric peripheral visual field loss: a randomized, crossover trial.

Purpose: To investigate the efficacy of our wearable night-vision aid in patients with concentric peripheral visual field loss.

Study design: Prospective, single blind, three-group, and three-period crossover clinical study.

Methods: The study included patients with concentric peripheral visual field loss, a best-corrected visual acuity (decimal visual acuity) of 0.1 or higher in the better eye, and the presence of a central visual field. HOYA MW10 HiKARI® (HOYA Corporation), our original wearable night-vision aid, was used as the test device with three types of camera lenses (standard-, middle-, and wide-angle lenses). Under both bright and dark conditions, the angle of the horizontal visual field was measured using each of the three lens types for each group. The baseline angle was measured when each participant wore the night-vision aid (powered off).

Results: The study included 21 participants. Under bright condition, the perceived horizontal visual field was significantly wider than the baseline setup when using the standard-angle lens ("the standard lens"); the middle-angle lens ("the middle lens") was significantly wider than both the baseline setup and the standard lens; and the wide-angle lens ("the wide lens") was significantly wider than the other lenses. Under dark condition, the perceived horizontal visual field was again significantly wider when using the middle lens than the baseline setup and the standard lens, and when using the wide lens, the perceived horizontal visual field was again wider than when using the other lenses. The control in the bright condition was significantly wider (p < 0.001) than when used in the dark condition, while the standard-angle lens in the dark condition was significantly wider (p = 0.05) than when used in the bright condition. In regards to the middle and wide lenses, there was no statistically significant result emerging from either of the illumination conditions.

Conclusion: Our wearable night-vision aid with a middle-angle or wide-angle lens appears to provide wider visual field images in patients with concentric peripheral visual field loss, regardless of whether the illumination conditions are bright or dark.