Background: To evaluate the short- and long-term effects of high-altitude hypobaric hypoxia on macula morphology and function during ascents, acclimatizations, and descents between 500 m and 5,650 m, macula function was evaluated in three healthy climbers of a trekking expedition. Methods: Macula physiology was tested with multifocal electroretinography (MF ERG), near and farvisual acuity, and Amsler grid tests. Macula morphology was tested with optical coherence tomography (OCT) and with stereoscopic fundoscopy obtained 1 week before ascent, as well as 1 week and 2 weeks after high-altitude exposure. The following physiological parameters indicative of acclimatization were compared daily during the expedition at altitudes between 500 m and 5,050 m: hemoglobin, oxygen saturation, resting heart rate, retinal findings, and the Lake Louise score of acclimatization. Results: The central macula MF ERG responses were significantly reduced 1 week after high-altitude exposure, and had recovered by the follow-up examination performed during the following week. Near visual acuity and Amsler grid tests remained unaffected at both follow-up examinations. No significant changes were found in the follow-up OCT and daily fundoscopy examinations in all three well-acclimatized climbers. Conclusions: High-altitude hypobaric hypoxia affects the function of the highly sensitive macula region. This suggests that the exposure of persons with macula diseases such as age-related macula degeneration, tapetoretinal degeneration, or diabetic retinopathy to high altitudes may influence the disease progression. For this reason, this population should avoid prolonged and unnecessary high-altitude exposure without proper acclimatization.

Keywords:
Macula dysfunction, High altitude, Multifocal electroretinography, Optical coherence tomography
1.
Honigman B, Theis MK, Koziol-McLain J, Roach R, Yip R, Houston C, Moore LG, Pearce P: Acute mountain sickness in a general tourist population at moderate altitudes. Ann Intern Med 1993;118:587–592.
2.
Frayser R, Houston CS, Bryan AC, Rennie ID, Gray G: Retinal hemorrhage at high altitude. N Engl J Med 1970;282:1183–1184.
3.
Lubin JR, Rennie D, Hackett P, Albert DM: High altitude retinal hemorrhage: a clinical and pathological case report. Ann Ophthalmol 1982;14:1071–1076.
4.
Brinchmann-Hansen O, Myhre K: Blood pressure, intraocular pressure, and retinal vessels after high altitude mountain exposure. Aviat Space Environ Med 1989;60:970–976.
5.
Frayser R, Houston CS, Gray GW, Bryan AC, Rennie ID: The response of the retinal circulation to altitude. Arch Intern Med 1971;127:608–611.
6.
Rennie D, Morrissey J: Retinal changes in Himalayan climbers. Arch Ophthalmol 1975;93:395–400.
7.
Wiedman M: High altitude retinal hemorrhage. Arch Ophthalmol 1975;93:401–403.
8.
Appleton F: Possible influence of altitude on blood pressure. Circulation 1967;36(suppl 11):35.
9.
Marticorena E, Ruiz L, Severino J, Galvez J, Penaloza D: Systemic blood pressure in white men born at sea level: changes after long residence at high altitudes. Am J Cardiol 1969;23:364–368.
10.
Canepa A, Chavez R, Hurtardo A, Rotta A, Velasquez T: Pulmonary circulation at sea level and at high altitudes. J Appl Physiol 1956;9:328–336.
11.
McFadden DM, Houston CS, Sutton JR, Powles AC, Gray GW, Roberts RS: High-altitude retinopathy. JAMA 1981;245:581–586.
12.
Lang GE, Kuba GB: High-altitude retinopathy. Am J Ophthalmol 1997;123:418–420.
13.
Sakamoto K, Yonoki Y, Kuwagata M, Saito M, Nakahara T, Ishii K: Histological protection against ischemia-reperfusion injury by early ischemic preconditioning in rat retina. Brain Res 2004;1015:154–160.
14.
Mack G, Uzel JL, Sahel J, Flament J: Multifocal electroretinogram for assessing sun damage following the solar eclipse of 11 August. J Fr Ophtalmol 2002;25:380–387.
15.
Brandl H, Lachenmayr B: Dependence of the sensitivity of the central visual field on hemoglobin-oxygen saturation. Ophthalmologe 1994;91:151–155.
16.
Carapancea M: ERG scotopic manifestation and their determinism, in experimental conditions of high altitude. Vision Res 1971;11:1219.
17.
Dolan FM, Parks S, Keating D, Dutton GN, Evans AL: Multifocal electroretinographic features of central retinal vein occlusion. Invest Ophthalmol Vis Sci 2003;44:4954–4959.
18.
Ohshima A, Hasegawa S, Takada R, Takagi M, Abe H: Multifocal electroretinograms in patients with branch retinal artery occlusion. Jpn J Ophthalmol 2001;45:516–522.
19.
Yotsukura J, Adachi-Usami E: Correlation of electroretinographic changes with visual prognosis in central retinal artery occlusion. Ophthalmologica 1993;207:13–18.
20.
Kang Derwent JJ, Linsenmeier RA: Hypoglycemia increases the sensitivity of the cat electroretinogram to hypoxemia. Vis Neurosci 2001;18:983–993.
21.
Dawis S, Hofmann H, Niemeyer G: The electroretinogram, standing potential and light peak of the perfused cat eye during acid-base changes. Vision Res 1985;25:1163–1177.
22.
Linsenmeier RA, Mines AH, Steinberg RH: Effects of hypoxia and hypercapnia on the light peak and electroretinogram of the cat. Invest Ophthalmol Vis Sci 1983;24:37–46.
23.
Mizota A, Adachi-Usami E: Effect of body temperature on electroretinogram of mice. Invest Ophthalmol Vis Sci 2002;43:3754–3757.
24.
Kobrick JL, Zwick H, Witt CE, Devine JA: Effects of extended hypoxia on night vision. Aviat Space Environ Med 1984;55:191–195.
25.
Kergoat H, Forcier P: Correlation of an exercise-induced increase in systemic circulation with neural retinal function in humans. Doc Ophthalmol 1996–97;92:145–157.
26.
Hirose F, Kiryu J, Miyamoto K, Nishijima K, Miyahara S, Katsuta H, Tamura H, Honda Y: In vivo evaluation of retinal injury after transient ischemia in hypertensive rats. Hypertension 2004;43:1098–1102.
27.
Ferrari R, Guardigli G, Mele D, Percoco GF, Ceconi C, Curello S: Oxidative stress during myocardial ischaemia and heart failure. Curr Pharm Des 2004;10:1699–1711.
28.
Grozdanic SD, Sakaguchi DS Kwon YH, Kardon RH, Sonea IM: Functional characterization of retina and optic nerve after acute ocular ischemia in rats. Invest Ophthalmol Vis Sci 2003;44:2597–2605.
29.
Kang Derwent J, Linsenmeier RA: Effects of hypoxemia on the a- and b-waves of the electroretinogram in the cat retina. Invest Ophthalmol Vis Sci 2000;41:3634–3642.
30.
Thanos S, Heiduschka P, Romann I: Exposure to a solar eclipse causes neuronal death in the retina. Graefes Arch Clin Exp Ophthalmol 2001;239:794–800
31.
Sakamoto Y, Kojima M, Sasaki K: Effectiveness of eyeglasses for protection against ultraviolet rays (in Japanese). Nippon Ganka Gakkai Zasshi 1999;103:379–385.
32.
Codenotti M, Patelli F, Brancato R: OCT findings in patients with retinopathy after watching a solar eclipse. Ophthalmologica 2002;216:463–466.
33.
Yap MK, Garner LF, Legg S, Faris J: Effects of exposure to simulated altitudes on visual fields, contrast sensitivity, and dazzle recovery. Aviat Space Environ Med 1995;66:243–246.
34.
Dain SJ: Sunglasses and sunglass standards. Clin Exp Optom 2003;86:77–90.
35.
Schmeisser ET, Gagliano DL, Santiago-Marini J: Visual system effects of exercise on Mauna Kea at 2,200 and 4,200 meters altitude. Mil Med 1997;162:186–189.
36.
Rai N, Thuladar L, Brandt F, Arden GB, Berninger TA: Solar retinopathy. A study from Nepal and from Germany. Doc Ophthalmol 1998;95:99–108.
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2005
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