Davies, Andrew J., Morris, D. S. (Dan S.), Kalson, N. S., Wright, A. D., Imray, C. (Chris) and Hogg, Chris R.. (2011) Changes to colour vision on exposure to high altitude. Journal of the Royal Army Medical Corps, Vol.157 (No.1). pp. 107-109. ISSN 0035-8665

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Abstract

Objectives: Several studies have shown deterioration in colour vision at altitudes above 3,000m. These studies have been conducted in photopic (bright daylight) conditions, whereas many military operations take place in mesopic (dim light) conditions. Data suggests that the tritan colour vision axis (blue cones, TA) are more susceptible to hypoxic insult than protan axis (red cones, PA). The objective of this study was to examine colour vision at high altitude, in mesopic conditions, and using a novel method of assessment to discriminate between the tritan and protan axis. Methods: We examined 42 eyes (21 subjects, mean age 44, range 22-71), at sea level and within 12-36 hours of exposure to 3300m. This was done in a darkened room, with refractive error correction. Colour vision was studied using ChromaTestTM, a software programme that analyzes colour contrast threshold (CCT) of both TA and PA. We planned to repeat CCT measurement at 4,392m, but technology failure prevented this. Non-parametric paired data was examined using the Wilcoxon signed rank test. Results: There was found to be no change to either the PA (p=0.409) or the TA (p=0.871) upon ascent. Within the PA 16 eyes had a lower CCT at high altitude, whilst 26 were higher. In the TA 20 eyes had a lower CCT and 22 were higher. At sea level, mean CCT for PA was 4.21 (SD 2.29) TA was 7.06 (SD 1.77). At 3,300m mean CCT for PA was 4.36 (SD 2.86) and TA was 6.93 (SD 2.39). Conclusions: This experiment revealed no changes to colour vision with exposure to 3,300m. This may be below the threshold altitude for cone dysfunction, alternatively colour vision deterioration may be less significant in mesopic conditions.

Item Type:	Journal Article
Subjects:	Q Science > QP Physiology R Medicine > RE Ophthalmology
Divisions:	Faculty of Medicine > Warwick Medical School
Library of Congress Subject Headings (LCSH):	Color vision, Color blindness, Altitude, Influence of
Journal or Publication Title:	Journal of the Royal Army Medical Corps
Publisher:	Royal Army Medical Corps
ISSN:	0035-8665
Date:	March 2011
Volume:	Vol.157
Number:	No.1
Page Range:	pp. 107-109
Status:	Peer Reviewed
Publication Status:	Published
References:	1. Rowe MH. Trichromatic color vision in primates. News Physiol Sci 2002;17: 93-98 2. Tekavcic-Pompe M, Tekavcic I. Colour vision in the Tritan Axis is predominantly affected at high altitude. High Alt Med Biol 2008;9(1): 38-42. 3. Karakucuk S, Oner AO, Goktas S, Siki E, Kose O. Colour vision changes in young subjects acutely exposed to 3,000m altitude. Aviat Space Environ Med 2004; 75(4):364-366. 4. Dean FM, Arden GB, Dornhorst A. Partial reversal of protan and tritan colour defects with inhaled oxygen in insulin dependent diabetic subjects. Br J Ophthalmol 1997;81: 27-30. 5. Wong R, Khan J, Adewoyin T, Sivaprasad S, Arden GB, Chong V. The ChromaTest, a digital color contrast sensitivity analyzer, for diabetic maculopathy: a pilot study. BMC Ophthalmol 2008;17: 8-25.
URI:	http://wrap.warwick.ac.uk/id/eprint/38466

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