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Changes in pupil dynamics at high altitude--an observational study using a handheld pupillometer
Mark H Wilson1, Mark Edsell, Chris Imray
1London Helicopter Emergency Medical Service, The Helipad, The Royal London Hospital, Whitechapel, London, UK. mark@rcsed.ac.uk
High Altitude Medicine & Biology
|January 1, 2009
Summary
Hypoxia from high altitude slows pupil function, affecting brain responses. A handheld pupillometer showed these changes, which normalized with acclimatization but did not correlate with acute mountain sickness.
Area of Science:
- Neuroscience
- Altitude Physiology
- Medical Devices
Background:
- Pupil dynamics offer insights into brain function.
- Hypoxia and intracranial pressure can alter pupillary light responses.
Purpose of the Study:
- To evaluate a portable pupillometer for field use.
- To investigate pupil dynamics changes under induced hypoxia at altitude.
- To correlate pupil changes with acute mountain sickness (AMS).
Main Methods:
- Seventeen volunteers were studied at 3450 m and 4770 m in Ladakh, India.
- A handheld pupillometer measured pupil size, latency, and constriction/dilatation velocities.
- Acute mountain sickness was assessed using Lake Louise questionnaires.
Main Results:
- Acute altitude exposure significantly reduced pupil size change and slowed constriction velocity.
- Pupillary latency increased significantly with altitude exposure.
- These effects reversed with acclimatization; no significant difference was found between subjects with and without AMS.
Conclusions:
- The handheld pupillometer is a robust field tool for monitoring pupil dynamics.
- Hypobaric hypoxia at moderate altitudes slows pupil function, which is reversible with acclimatization.
- Hypoxia affects cerebral function, but these changes did not correlate with moderate AMS.
