Short- and middle-term high-altitude exposure does not affect visual acuity and contrast sensitivity of healthy young people

Abstract

Objective: Visual acuity and contrast sensitivity are crucial for optimal performance and safe sport activity. From a practical sport-specific perspective, visual performance is obligatory for orientation and movement control in mountainous areas. The purpose of this study was to analyze the effect of hypobaric hypoxic conditions on visual acuity and contrast sensitivity of short-term and middle-term acclimatized healthy young people.

Design: This study used a repeated-measure design with ten eye-healthy and physically active students representing different types of sports.

Methods: With the help of a computer-based Landolt C and a Sine Wave Contrast test, visual performance was investigated similar before (156 m), during a nine-day high-altitude sojourn (sleeping level: 890-4640 m), and three months later (156 m). All tests were performed under standardized illumination conditions. Additionally, morning blood oxygen saturation, hematocrits, hemoglobin, body mass, and self-reported symptoms of acute mountain sickness criteria were determined.

Results: Whole blood oxygen saturation declined during altitude exposure. The analysis of central visual performance at altitude showed no effect of hypobaric hypoxia.

Conclusion: Our data suggest that activity in a hypobaric hypoxia condition at moderate to high altitude levels of up to 4600 m does not affect visual acuity and contrast sensitivity of acclimatized healthy young people. However, in contrast to previous studies that outlined acutely impaired central visual performance with respect to hypoxia, we suggest that acclimatization might induce adaptation of visual perception performance and therefore reduce the risk of accidents resulting from partial loss of visual performance at altitude.

Keywords: Altitude; Central vision; Freiburg visual acuity test; Hypoxia; Snow sport; Visual perception.