Retinal vessel regulation at high altitudes¹

Issue title: HYPOXIA

Guest editors: F. Jung and C. Jung

Article type: Research Article

Authors: Neumann, Thomas^{a; *} | Baertschi, Michael^{b; c} | Vilser, Walthard^d | Drinda, Stefan^e | Franz, Marcus^f | Brückmann, Andreas^g | Wolf, Gunter^a | Jung, Christian^h

Affiliations: [a] Department of Internal Medicine III, Jena University Hospital, Jena, Germany | [b] Department of Ophthalmology, University of Basel, Switzerland | [c] Eyeness AG, Bern, Switzerland | [d] IMEDOS Systems UG, Jena, Germany | [e] Klinik Buchinger Wilhelmi, Überlingen, Germany | [f] Department of Internal Medicine I, Jena University Hospital, Jena, Germany | [g] Department of Prenatal Diagnosis and Preventive Medicine, GesaTal Medical Center, Erfurt, Germany | [h] University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Medical Faculty, Division of Cardiology, Pulmonology and Vascular Medicine, Düsseldorf, Germany

Correspondence: [*] Corresponding author: Thomas Neumann, MD, Klinik für Innere Medizin III, Erlanger Allee 101, Universitätsklinikum Jena, 07747 Jena, Germany. Tel.: +49 3641 9324595; Fax: +49 3641 9324355; E-mail: [email protected].

Note: [1] The study was conducted according to the principles of the Declaration of Helsinki.

Abstract: PURPOSE: To measure static and dynamic changes of retinal vessels in response to normobaric hypoxia (NH, study A) and hypobaric hypoxia (HH, study B). METHODS: Study A included 10 healthy individuals exposed to a simulated altitude of 5500 meters in a NH chamber; study B included 17 individuals studied after ascent to 3000-meter altitude. Retinal vessel diameter, response to flicker light, retinal oxygen saturation and retinal venous pressure were measured at baseline, under the corresponding hypoxia condition. The effects of macitentan, an endothelin receptor antagonist, were examined in study B. RESULTS: The mean age of participants was 34.6±9.3 years in study A and 36.7±10.8 years in study B. Retinal arterial and venous diameter increased, arterial and venous response to flicker light decreased, while retinal oxygen saturation remained stable under both experimental conditions. Retinal venous pressure increased in six individuals after ascent to 3000 meters and normalized after macitentan treatment. The occurrence of acute mountain sickness (AMS) correlated only with the decrease of arterial constriction after ascent to 3000 meters. CONCLUSIONS: Retinal arterial and venous vessels react to NH and HH with a diameter increase and an impaired response to flicker light. Macitentan was capable to normalize the increased retinal venous pressure observed at high altitudes.

Keywords: Digital vessel analysis, retinal, hypoxia, high altitude, macitentan, retinal venous pressure

DOI: 10.3233/CH-162041

Journal: Clinical Hemorheology and Microcirculation, vol. 63, no. 3, pp. 281-292, 2016