Mild hypoxia impairs chromatic sensitivity in the mesopic range.

Area of Science:

• Ophthalmology
• Human Physiology
• Visual Neuroscience

Background:

• Chromatic sensitivity in the mesopic visual range is critical for daily tasks.
• The impact of altered oxygen levels (hypoxia and hyperoxia) on mesopic chromatic vision remains under-investigated.

Purpose of the Study:

• To investigate the effects of mild hypoxia and hyperoxia on red-green (R-G) and yellow-blue (Y-B) chromatic sensitivity thresholds.
• To assess these effects across different luminance levels: low photopic, borderline upper mesopic, and mid-mesopic.

Main Methods:

• Utilized the Color Assessment and Diagnosis (CAD) test with dynamic luminance contrast noise to measure R-G and Y-B chromatic sensitivity.
• Induced mild hypoxia by breathing 14.1% oxygen and hyperoxia by breathing 100% oxygen.
• Employed a balanced, repeated-measures design with MANOVA for statistical analysis.

Main Results:

• Luminance level, viewing condition (binocular vs. monocular), and oxygenation state significantly influenced chromatic sensitivity.
• Observed progressive impairment of chromatic sensitivity with decreasing luminance under mild hypoxia.
• Identified gender-specific variations and noted the CAD test's sensitivity to pre-existing color vision deficiencies.

Conclusions:

• Mild hypoxia progressively diminishes chromatic sensitivity in the mesopic range as luminance decreases.
• Binocular summation of chromatic signals is reliable and unaffected by the luminance channel.
• The CAD test demonstrates high sensitivity for detecting both congenital and acquired color vision deficits.