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Intraocular pressure and acclimatization to 4300 M altitude
A Cymerman1, P B Rock, S R Muza
1Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, USA. allen.cymerman@na.amedd.army.mil
Aviation, Space, and Environmental Medicine
|October 29, 2000
Summary
Altitude exposure significantly reduces intraocular pressure (IOP), with lower IOP correlating to acute mountain sickness (AMS) severity. IOP changes may offer an objective measure of hypoxic stress response.
Area of Science:
- Environmental Physiology
- Ophthalmology
- Altitude Medicine
Background:
- Studies investigated the impact of high altitude on intraocular pressure (IOP).
- The relationship between IOP and acute mountain sickness (AMS) severity was explored.
Purpose of the Study:
- To determine how altitude exposure affects IOP.
- To examine the correlation between IOP and AMS severity.
- To investigate the link between urinary catecholamines and IOP changes.
Main Methods:
- Intraocular pressure (IOP) was measured using tonometry in males and females during simulated altitude exposure.
- Urinary catecholamines and AMS severity (Environmental Symptoms Questionnaire - ESQ-C) were assessed.
- Studies involved acute exposure and acclimatization periods at simulated high altitude (4300 m).
Main Results:
- IOP decreased significantly within hours of altitude exposure (25% in Study A, 13% in Study B).
- IOP returned towards sea level values during acclimatization (15 days).
- A positive correlation was found between IOP and AMS severity, and between reduced IOP and urinary epinephrine concentrations.
Conclusions:
- Altitude exposure acutely reduces IOP, with recovery during acclimatization.
- Epinephrine concentration increases may contribute to IOP reduction.
- IOP measurement could serve as an objective indicator of an individual's response to hypoxic stress.