High Altitude Retinal Hemorrhage

Wiedman, Michael

doi:10.1001/archopht.1975.01010020415002

Cited by 57 publications

(31 citation statements)

References 12 publications

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“…The higher number of patients with dilated and tortuous retinal vessels could be because of normal response to hypoxia as reported in other studies from high altitude (Morris et al, 2006;Mc. Fadden et al, 1981;Braun et al, 1997;Wiedman, 1975). Diabetic retinopathy was not found among three known diabetics and two newly diagnosed cases detected while systemic evaluation for retinal vein occlusion in our series, unlike in the previous study done at same district where diabetic retinopathy was present in all two cases (Ulrich et al, 2009).…”

Section: Discussioncontrasting

confidence: 46%

Vitreo-retinal disorders at high altitude in Nepal

Thapa

Poudyal

et al. 2013

Nep J Oph

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Introduction: Nepal has many mountains including the highest one in the world. People living in high altitude are often involved in climbing mountains. Objective: To explore the pattern of vitreo-retinal disorders at high altitude in Nepal. Materials and methods: Consecutive patients aged 40 years and older who presented at the micro-surgical eye camp at Lukla of Solukhumbu district (2,860 metres) were included. Detailed ocular and systemic histories and ocular examination including dilated fundus evaluation were done. Results: There were a total 81 patients with the mean age of 56.7 years (S.D 11.15). Females (51.9 %) outnumbered males. Sherpa comprised of 76.5 % followed by Rai (9.8 %). The main occupation was agriculture (51.9 %) followed by mountain trekking (28.4 %). Smokers comprised of 13.5 %. Hypertension was the predominant systemic problem (28 %). The best corrected visual acuity of 6/18 and better was found in 86.4 % of cases and less than 3/ 60 in 3.6 % of cases. Age-related macular degeneration (AMD) was found in 19.6 % of cases with a predominant mild AMD (16 %), hypertensive retinopathy in 12.2 %, with grade I hypertensive change in 8.6 %, retinal vein occlusion (RVO) in 7.1 % of cases and with a branch RVO in 4.9 %. Dilated and tortuous retinal vessels were present in 25.9 % of cases; out of this, 9.8 % of the cases had concurrent AMD and/or hypertensive retinopathy. Other retinal problems were macular hole (2.46 %), solar retinopathy (2.46 %) and choroidal tear (1.2 %). Conclusion: AMD, hypertensive retinopathy, and RVO are the main vitreo-retinal disorders besides the dilated and tortuous retinal vessels in people living at high altitude in Nepal.

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Section: Discussioncontrasting

confidence: 46%

Vitreo-retinal disorders at high altitude in Nepal

Thapa

Poudyal

et al. 2013

Nep J Oph

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“…Studies in mountaineers revealed that an ascent to high altitude may cause morphological and functional changes of the retina, such as optic disc swelling, changes of macular function including color discrimination, altered retinal and choroidal blood flow, and retinal hemorrhages (Frayser et al, 1970;Wiedman, 1975;Pavlidis et al, 2005;Morris et al, 2007;Bosch et al, 2008Bosch et al, , 2009Willmann et al, 2010Willmann et al, , 2011Ho et al, 2011;Fischer et al, 2012). While some of these changes present physiological adaptive mechanisms to high altitude exposure such as increased blood flow and increased tortuosity of blood vessels, others present potentially pathological changes to hypoxia, such as optic disc swelling or retinal hemorrhages.…”

Section: High Altitude-associated Changesmentioning

confidence: 99%

Hypoxia in the Eye: A Two-Sided Coin

Grimm

Willmann

2012

High Altitude Medicine & Biology

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Grimm, Christian, Gabriel Willman. Hypoxia in the eye: A two-sided coin. High Alt Med Biol. 13:169-175, 2012.-Tissue oxygenation in general and hypoxia in particular are important regulators of retinal physiology and pathophysiology. Reduced oxygen tension and hypoxia-inducible transcription factors along with some of their target genes are critically involved in retinal development, and especially in the generation of a normal retinal vasculature. Well-timed hypoxia is thus vital for the young eye to establish proper retinal function and vision. However, when hypoxia is ill-timed, reduced oxygen tension may be associated with the development of retinal pathologies, including retinopathy of prematurity, diabetic retinopathy, glaucoma, age-related macular degeneration, or high altitude retinopathy. Here, reduced oxygen tension activates a hypoxic response that culminates in an increased expression of vascular endothelial growth factor. This causes pathological neovascularization of the delicate neuronal retina, a process that may ultimately lead to loss of vision. In contrast, preconditioning by welldefined and controlled short-term hypoxia is not devastating for the retina but instead induces a molecular response that provides protection to neuronal cells. Detailed investigation of hypoxic mechanisms during development and adulthood may thus reveal factors, which may be targeted by therapeutic approaches to save and preserve vision in patients.

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“…In this respect, the retina provides a microvascular bed which is easily accessible for in vivo studies in man. Experimental stud ies of acute hypoxia3-7 and long-term hypoxia in subjects participating in mountaineering expeditions, [8][9][10][11] have documented that hypo baric hypoxia dilates both retinal arteries and veins. Vasodilation and increased blood flow improve oxygen transport to the retina, and as such it represents a beneficial mechanism determined by local needs of the eye.…”

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confidence: 99%

Retinal vessel responses to exercise and hypoxia before and after high altitude acclimatisation

Brinchmann‐Hansen

Myhre

Sandvik

1989

Eye

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SummaryComputerised microdensitometry was used to study diameter changes in 93 arterial and 91 venous vessel sites in the retinas of four mountain climbers before and after spending seven weeks in the Himalaya mountains. The vascular response to short term strenuous exercise was measured at sea level, to acute hypoxia of simulated alti tude of 15,000 ft (4,572 m) at rest, and to strenuous exercise while acutely exposed to the same hypoxic condition. Before the mountain exposure, retinal vessels con stricted during exercise -1.9% (arteries); -3.3% (veins) and dilated in acute hypo xia 9.4% (arteries); 8.1 % (veins). Superimposed exercise on hypoxic dilated arteries reduced the vasodilation (9.4% to 6%). After acclimatisation, the same physical work load at sea level constricted the arteries more (-5.4% vs -1.9%) but did not constrict the veins (0.2% vs -3.3%). Superimposed exercise on hypoxic dilated vessels, excessively dilated both arteries (8.4% vs 6.0%) and veins (13.7% vs 8.4%), compared to changes seen before the mountain sojourn. This study shows that phys ical conditioning and long adaptation to hypoxia, significantly change the vascular response of the retina to physical activity both in normal atmospheric conditions and during hypoxic stress. High altitude retinal hemorrhages (HARH) were present in one climber, and the study may indicate why HARH is seen often in young and phys ical well-trained subjects. RETINAL VESSEL RESPONSES TO EXERCISE 769reflect the autoregulatory ability of the eye to withstand elevated flow caused by changes in the systemic circulation.In the present paper, calibre changes of ret inal arteries and veins were studied in physical exercise at sea level, in acute exposure to hypoxia, and in physical exercise super imposed on already hypoxic dilated vessels. The subjects were exposed to identical test protocol before and after seven weeks of strenuous mountain climbing in the Himalaya mountains. We observed that high altitude acclimatisation significantly altered the acute response of retinal circulation to physical exercise both in a hypoxic environment and at sea level. Subjects and methods SubjectsFour male mountaineers, aged 33 (no.1), 42 (no. 2), 64 (no. 3), and 42 (no. 4) (mean: 45) years, were used in the study. One of the sub jects (no. 2) lived 800 m above sea level, while the rest of the group lived at sea level. The youngest climber had not previously been exposed to high altitude, while the others were experienced mountaineers from several expeditions above 5,000 m. None of these expeditions, however, had taken place within the past three years.General medical and eye examinations were performed, and the subjects were found to be in good health. The blood pressure was measured by auscultation in a sitting position after 10 minutes rest. The systolic pressure averaged 142 ± 9 (SD) mmHg and the dias tolic pressure 80 ± 8 mmHg. The intraocular pressure, measured by applanation tono metry in the sitting position, averaged 12 ±

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High Altitude Retinal Hemorrhage

Cited by 57 publications

References 12 publications

Vitreo-retinal disorders at high altitude in Nepal

Vitreo-retinal disorders at high altitude in Nepal

Hypoxia in the Eye: A Two-Sided Coin

Retinal vessel responses to exercise and hypoxia before and after high altitude acclimatisation

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