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Changes in pupil dynamics at high altitude — an observational study using a handheld pupillometer
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Wilson, Mark H., Edsell, Mark, Imray, C. (Chris) and Wright, Alex (2008) Changes in pupil dynamics at high altitude — an observational study using a handheld pupillometer. High Altitude Medicine & Biology, Vol.9 (No.4). pp. 319-325. doi:10.1089/ham.2008.1026 ISSN 1527-0297.
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Official URL: http://dx.doi.org/10.1089/ham.2008.1026
Abstract
Wilson, Mark H., Mark Edsell, Chris Imray, Alex Wright, and the Birmingham Medical Research Expeditionary Society. Changes in pupil dynamics at high altitude—an observational study using a handheld pupillometer. High Alt. Med. Biol. 9:319–325, 2008. Gross pupil dynamics are used as an indirect measure of brain function. Changes in hypoxia and intracranial pressure are thought to alter pupil responses to light. This study assessed a portable handheld pupil measuring device (pupillometer) in the field investigating the changes in pupil size, speed of reaction, and rate of constriction/dilatation with hypoxia induced by changes in altitude. A correlation between pupil dynamics and acute mountain sickness was sought. Seventeen volunteers were studied following acute exposure to 3450 m and then during a trek to 4770 m in Ladakh, India. The pupillometer was used to record maximum and minimum pupil diameter in response to a standard light source with calculation of latency, constriction and dilatation velocities. Acute mountain sickness (AMS) was recorded using Lake Louise self completed questionnaires both in the morning and afternoon on each day. Acute altitude exposure resulted in a significant reduction of percentage change in pupil size (36.5% to 24.1% p = <0.001), significant delay in pupillary contraction (latency; 0.208 to 0.223 seconds p = 0.015) and a significant slowing of the rate of contraction (constriction velocity; −2.77 mm/s to −1.75 mm/s p = 0.012). These changes reverted to normal during a period of acclimatization. A significant diurnal variation in pupil size was also observed. There was no significant difference between subjects with and without AMS. The handheld pupillometer is a suitable robust tool for monitoring changes in pupil dynamics in the field. With acute exposure to hypobaric hypoxia associated with an ascent to a moderate altitude, there is a general slowing of pupil function which reverts to normal within a few days of acclimatization. There appears to be a marked diurnal variation in pupil size. The measurements clearly demonstrated an effect of hypoxia on cerebral function, but these changes did not relate to moderate AMS.
| Item Type: | Journal Article | ||||
|---|---|---|---|---|---|
| Divisions: | Faculty of Science, Engineering and Medicine > Medicine > Warwick Medical School > Biomedical Sciences > Translational & Experimental Medicine > Metabolic and Vascular Health (- until July 2016) Faculty of Science, Engineering and Medicine > Medicine > Warwick Medical School |
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| Journal or Publication Title: | High Altitude Medicine & Biology | ||||
| Publisher: | Mary Ann Liebert, Inc. Publishers | ||||
| ISSN: | 1527-0297 | ||||
| Official Date: | 30 December 2008 | ||||
| Dates: |
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| Volume: | Vol.9 | ||||
| Number: | No.4 | ||||
| Page Range: | pp. 319-325 | ||||
| DOI: | 10.1089/ham.2008.1026 | ||||
| Status: | Peer Reviewed | ||||
| Publication Status: | Published | ||||
| Access rights to Published version: | Restricted or Subscription Access |
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