Hypobaric hypoxia: effects on contrast sensitivity in high altitude environments.

Area of Science:

• Aviation physiology
• Ophthalmology
• Environmental medicine

Background:

• Hypobarism and hypoxia are known to affect visual performance, particularly contrast sensitivity (CS).
• Previous research established the link between reduced atmospheric pressure and visual function changes.

Purpose of the Study:

• To investigate corneal thickness adjustments in hypobaric hypoxia.
• To compare these corneal changes with alterations in contrast sensitivity.

Main Methods:

• 12 healthy, emmetropic aircrew subjects were studied.
• Central corneal thickness (CCT) was measured using ultrasonic pachymetry.
• Contrast sensitivity (CS) was assessed using Pelli-Robson charts under varying atmospheric and oxygen pressures.

Main Results:

• Hypobaric hypoxia significantly increased CCT from 550 μm to 600 μm.
• Contrast sensitivity (CS) significantly decreased from 1.95 log to 1.05 log.
• A statistically significant correlation was observed between CCT changes and CS reduction.

Conclusions:

• Hypoxia and atmospheric pressure variations can induce corneal edema.
• These corneal changes are associated with a reduction in contrast sensitivity.
• Findings suggest potential implications for visual performance in aviators.