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Mehmet Karakucuk, Burcu Polat, Ertugrul Mirza, Hatice Arda, Koray Gumus, Ayse Oner; Contrast Sensitivity, Electroretinography and Optical Coherence Tomography Changes in Young Subjects After an Acute Unacclimatized Short Exposure to High Altitude. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5327.
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© ARVO (1962-2015); The Authors (2016-present)
Changes in visual integrity during prolonged unacclimatized ascent to high altitudes (over 8000ft/2438m) maybe of concern in mountaineering, outdoor sports, military operations or aviation related duties such as those involving unpressurized flights. However, it is not known whether these changes can occur after relatively short exposures to high altitudes and continue a few days after the exposure. Here we present the first evaluation of retinal changes after an acute unacclimatized and short (approximately 3 hours) exposure to high altitude at the 2630m/8628ft-2650m/8694ft range.
Contrast sensitivity testing, electroretinography (ERG) and optical coherence tomography (OCT) were performed on twenty-three healthy subjects aged between 17-29 years (mean age ±S.E.M = 20.88±0.64 years) at the Eye clinic of Erciyes University Faculty of Medicine which is located at an altitude of 1080m/3543ft. On the following week, during a one-day-activity, the subjects were transported from 1080m/3543ft to a station at 2630m/8628ft on Mt. Erciyes by buses and cable-cars within one hour. After resting for one hour at 2630m/8628ft, the group started to climb by a moderate pace, reached 2650m/8694ft altitude, completed a route within 2 hr. and returned back to 2630m/8628ft. The group overall spent 3 hours at high altitude (2630m/8628ft-2650m/8694ft range) and were transported back to the city. The same set of tests were repeated within the 3 days following the altitude exposure. The test results before and after the altitude exposure were compared with each other.
Average pre-exposure contrast sensitivity on the 20/25 scale was 0.12 logMar units on the right and 0.13 logMar units on the left eyes. After the altitude exposure, these values decreased to 0.14 logMar units (p=0.02) and 0.14 log mar units (p=0.01), on the right and left eyes, respectively. Average pre-exposure ERG flicker amplitude on the left eyes was 58.64mV and decreased to 52.05mV after the altitude exposure (p=0.05). No significant differences were observed in the OCT values between the pre- and post exposure values.
Acute unacclimatized short exposure to high altitude can negatively affect some of the photopic photoreceptor functions in young subjects and this effect can last a few days following the exposure.
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