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Retinal Vascular Changes in Response to Hypoxia: A High-Altitude Expedition Study
Jessica Westwood1, India Mayhook-Walker1, Ciaran Simpkins1
1Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom.
High Altitude Medicine & Biology
|November 27, 2023
Summary
High-altitude exposure caused physiological changes in retinal vasculature, increasing vessel diameter and tortuosity. No high-altitude retinopathy (HAR) occurred, indicating adaptive responses in healthy individuals.
Area of Science:
- Ophthalmology
- Altitude Medicine
- Physiology
Background:
- Hypoxia at high altitudes can cause retinal vascular changes, potentially leading to high-altitude retinopathy (HAR).
- Understanding the precise mechanisms and incidence of HAR requires further quantitative investigation.
Purpose of the Study:
- To quantitatively assess retinal vascular changes in response to acute hypoxia during a high-altitude expedition.
- To evaluate the relationship between altitude exposure and specific retinal vessel parameters.
Main Methods:
- Ten healthy participants underwent daily fundus imaging during a 4,167m expedition.
- Retinal vessel diameter, tortuosity, and density were measured and analyzed.
- High-altitude retinopathy (HAR) features were assessed.
Main Results:
- Significant increases in retinal vessel tortuosity and diameter were observed with increasing altitude.
- A strong correlation was found between altitude and supratemporal retinal artery diameter.
- Median vessel density increased significantly from baseline to summit day, with no incidences of HAR.
Conclusions:
- The study observed physiological, but not pathological, retinal vascular changes in response to moderate altitude exposure.
- These adaptive changes suggest effective physiological responses in healthy individuals under these conditions.
- Future research should explore higher altitudes and control for environmental factors to better understand HAR etiology.
