Title : Altitude induced color vision impairment: A novel rapid hue discrimination assay for acute hypoxic exposure
Abstract:
Purpose: To quantify and track acute changes in hue discrimination under simulated high-altitude (3,500–4,500 m) low-pressure hypoxia, and to validate a new rapid, software-based test that overcomes the portability and time limits of the Farnsworth-Munsell 100-Hue test.
Methods: Fourteen healthy adults with normal color vision in hypobaric chamber. Eight sequential conditions (ground → 3,500 m → 4,000 m → … → ground) were tested. Custom “Rapid Hue-Discrimination System” (Toward Pi Ltd.) running on a 14-inch calibrated 120 Hz display. 7 wavelength bands (400–700 nm) tested; minimum hue difference (MHD) resolvable recorded (1 nm precision).
Results: Red light showed the poorest and most variable discrimination (MHD 28.7 → 22.4 nm). Forty minutes of altitude acclimatization significantly improved cyan and purple discrimination (MHD reduced by 20–35 %) but slightly worsened orange and yellow, while other bands remained stable. The overall wavelength-MHD curve preserved the classic pattern with troughs at ~500 nm and ~600 nm and peaks near 550 nm and after 620 nm. Normalized score explained 81 % of MHD variance. Testing time dropped from 25 s per hue on first exposure to 8–10 s thereafter, yielding a total test duration of ≈5 min and confirming the tool’s efficiency and robustness.
Conclusions: Acute hypoxia selectively degrades red-light discrimination, while short acclimatization benefits cyan and purple hues. The software-based assay delivers clinically relevant metrics (MHD + score) within ~5 min, feasible for cockpit, alpine, or space environments.
