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Decreased contrast sensitivity at high altitude.

Katrin Gekeler1, Andreas Schatz1,2, Manuel Dominik Fischer1,2

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High altitude exposure significantly decreased contrast sensitivity (CS) in healthy subjects, independent of acute mountain sickness (AMS). This visual change impacts trekkers and mountaineers, altering visual processing in low light conditions.

Keywords:
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Area of Science:

  • Ophthalmology
  • Altitude Medicine
  • Human Physiology

Background:

  • High altitude exposure presents challenges to human physiology.
  • Hypobaric hypoxia at altitude can affect sensory functions.
  • Previous studies have explored altitude's impact on vision.

Purpose of the Study:

  • To investigate changes in visual acuity and contrast sensitivity (CS) during high altitude exposure.
  • To assess the effects of hypobaric hypoxia on visual function in healthy individuals.
  • To relate visual changes to physiological parameters like oxygen saturation.

Main Methods:

  • 14 healthy subjects were tested at high altitude (4559m) and compared to baseline (341m).
  • Visual acuity and Weber CS were measured using the Freiburger Visual Acuity and Contrast Test.
  • Peripheral oxygen saturation (SpO2), heart rate (HR), and acute mountain sickness (AMS) scores were recorded and correlated with visual tests.

Main Results:

  • A significant decrease in Weber CS was observed at high altitude (mean effect size -0.13 logCS).
  • Visual acuity remained unchanged throughout the study.
  • Decreased CS correlated with reduced SpO2 but not with HR or AMS scores.

Conclusions:

  • High altitude exposure leads to a measurable decrease in contrast sensitivity.
  • These visual changes occur independently of acute mountain sickness.
  • Findings are clinically relevant for individuals exposed to high altitudes, affecting vision in low light and offering insights into hypoxia's effects on CS.