Purchase this article with an account.
Alexander F. Scheuerle, Kai Schommer, Gerd U. Auffarth, Peter Bärtsch; HRT Detects Optic Disc Swelling In Acute Mountain Sickness. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5310.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Acute mountain sickness (AMS) is caused by acute exposure to low partial pressure of oxygen that typically occurs at high altitude. It commonly occurs at elevations above 3000m and often presents non-specific symptoms with headache or sleep distrubance and may progress to progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE). The optic nerve is part of the central nervous system and might be affected by AMS. The Heidelberg Retina Tomograph (HRT) is suitable for precise in-vivo imaging of the optic disc. This study was performed to investigate if changes of the optic disc secondary to AMS can be detected by means of HRT.
A hypoxic cabin was used to simulate high altitude. A total of 30 volunteers were exposed to a gradually lowered partial pressure of oxygen and proportionally increased partial pressure of nitrogen that resembled a rapid ascent up to 4000m. The total time of exposure was 20hours. The Heidelberg Retina Tomograph (HRT III) was used for imaging of the optic disc and the parapapillary retina of both eyes before exposure, after 6hours, 16hours and after 36hours. Topographic change analysis (TCA) was applied to measure changes of volume and area within the automatically defined clusters.
The mean age of the volunteers was 26.2years ± 5.4. All subjects were able to complete the total time of exposure to hypoxia. A total of 60 eyes were studied before exposure, after 6hours, after 16hours and after 36hours. Each time three HRT mean images were acquired and analyzed. Image quality was excellent with SD 11.6µ ± 4.2. TCA showed the following clusters with changes referring to the first examination: Volume (10-3 mm3) increased by 25.88 after 6hours, 31.53 after 16hours and 3.25 after 36hours. Area (mm2) increased by 0.45 after 6hours, 0.66 after 16hours and 0.08 after 36hours.
A hypoxic cabin was used to simulate a rapid ascent to high altitude in order to cause symptoms of AMS. Despite the short time of expose, changes of the surface of the optic disc could be detected by HRT imaging in the majority of eyes. The changes within the TCA clusters were relatively small. Changes of volume and area increased with time of exposure to reduced oxygen levels and formed back after the return to sea level. We report the first study that introduced HRT imaging to detect subtle and temporary changes of the optic disc that occur secondary to AMS. Further investigations are necessary to evaluate the relationship between the changes of the optic disc and the extent of clincal symptoms of AMS.
This PDF is available to Subscribers Only