Visual Improvements after Perceptual Learning Transfer from Normoxia to Hypoxia

ABSTRACT Objective: This study aimed to evaluate vision improvement in hypoxia following normoxic perceptual learning. Background: Visual functions are important for flight safety. However, the potential of perceptual learning to compensate for hypoxic vision damage is unclear. Method: Seven observers enrolled in this study and were exposed to a hypoxic (11.5% O2) and a mesopic (3 cd/m2) environment. Visual acuity (VA) and contrast sensitivity function (CSF) were evaluated in normoxia and hypoxia before and after the 8 daily training sessions. All observers trained in a monocular sine-wave grating detection task near their individual cutoff spatial frequencies while breathing normoxic gas. Results: The contrast sensitivity (CS) at the trained spatial frequency, the area under the log CSF (AULCSF) and VA decreased in a hypoxic environment. Additionally, all visual performances (i.e., CS, AULCSF and VA), regardless of whether they were measured in the normoxic or hypoxic condition, improved following normoxic perceptual learning. The degree of visual improvement did not differ between normoxia and hypoxia, indicating that visual improvement is completely transferable from normoxia to hypoxia. Conclusions: Preliminary evidence suggests that visual improvement remains even under environmental changes, and perceptual learning may be a noninvasive way to compensate for vision decreases in hypoxia.