Corneal thickness at high altitude

Daniel S. Morris, J. E A Somner, Kirsten M. Scott, I. J C McCormick, Peter Aspinall, Baljean Dhillon

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    42 Citations (Scopus)


    PURPOSE: The eye, like other organs, is affected by the hypobaric hypoxia of high altitude. Corneal swelling is known to occur under hypoxic conditions at sea level, for instance when wearing contact lenses. The aim of this study was to measure central corneal thickness (CCT) in lowlanders ascending to altitude. METHODS: The Apex 2 medical research expedition provided the opportunity to measure CCT in 63 healthy lowlanders. The subjects arrived in La Paz, Bolivia (3700 m), where they spent 4 days acclimatizing before being driven over 2 hours to the Cosmic Physics Laboratory at Chacaltaya (5200 m), where they stayed for 7 days. CCT was measured in the early afternoon by using ultrasound pachymetry on the first, third, and seventh day at 5200 m and before and after the expedition at sea level. RESULTS: Mean CCT increased significantly from 543 µm at sea level to 561 µm on the first day at 5200 m (P < 0.001). This continued to increase to 563 µm on the third day and 571 µm on the seventh day but returned to 541 µm after descent to sea level. CONCLUSIONS: This study showed that altitude caused a significant increase in CCT in a large group of healthy lowlanders with normal corneas. This finding confirms the results of previous studies and is likely to be caused by endothelial dysfunction causing stromal swelling. This could potentially cause visual problems for high-altitude mountaineers among whom refractive surgery is popular. © 2007 Lippincott Williams & Wilkins, Inc.

    Original languageEnglish
    Pages (from-to)308-311
    Number of pages4
    Issue number3
    Publication statusPublished - Apr 2007


    • Altitude
    • Corneal pachymetry
    • Endothelial dysfunction
    • Hypoxia
    • Refractive surgery


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