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Gabriel Willmann, Andreas Schatz, M Dominik Fischer, Kai Schommer, Ahmad Zhour, Marie L. Marhoefer, Karl U. Bartz-Schmidt, Eberhart Zrenner, Florian Gekeler; Dry Eye Syndrome During Acute High Altitude Exposure. Invest. Ophthalmol. Vis. Sci. 2012;53(14):557.
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High altitude exposure (HAE) is -due to constantly rising numbers of mountaineers and trekkers- a clinically relevant cause of complex pathophysiological events leading to alterations in all parts of the visual system. The purpose of this study was to evaluate the effects of acute HAE on tear film assessing its osmolarity, tear film break up time (TBUT), Schirmer test as well as high resolution imaging of tear film thickness.
Eighteen healthy lowlanders ascended from Tübingen (341m, Germany) to the Capanna Margherita (CM; 4554m, Italy) during the Tübingen High Altitude Ophthalmology (THAO) research expedition within 24 hours including one overnight stay at 3611m. Tear film osmolarity (TearLab, San Diego, CA, USA; n = 14) of the right eye, TBUT and Schirmer test (n = 18) without anesthesia of both eyes were assessed on day 1, 2 and 4 during high altitude exposure under standardized conditions at the CM. In addition, a Spectralis anterior segment module (Heidelberg Engineering, Heidelberg, Germany; n = 14) was used to measure tear film thickness on day 1 and 3 at high altitude. Baseline recordings were taken before (BL1) and at least 2 weeks after HAE (BL2) at the University Eye Hospital in Tübingen. Intra-individual ratios were calculated using MANOVA with a significance level of p < 0.05.
Upon arrival at CM, a significant increase in intra-individual ratios of tear film osmolarity (day1: 8.0%, 95% confidence interval (CI) 2.1-13.8%; day2: 9.0%, CI 2.3-15.6%; day4: 7.1%, CI 1.8-12.4%) and a significant decrease of TBUT (day1: 31.2%, CI 4.8-57.7%; day2: 46.1%, CI 74.1-26.0%; day4: 55.2%, CI 43.5-66.8%) was noted compared to baseline recordings. Schirmer test at high altitude remained non significant compared to baseline. High resolution imaging of the tear film showed a clear trend towards decreased tear film thickness without reaching statistical significance on both days measured. Measurements at BL1 and BL2 showed no statistically significant differences and recordings of right and left eyes for TBUT and Schirmer did not differ significantly on each day measured.
Acute high altitude exposure leads to a dry eye syndrome. Tear film osmolarity followed by TBUT were found to be the most informative and reliable markers. This is of clinical importance to trekkers and mountaineers exposed to high altitude since possible disturbance of vision with dry eye symptoms may be a potential risk factor at high altitude. Application of artificial tears may be advisable and improve dry eye symptoms during high altitude exposure.
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