ArticleInvestigative ophthalmology & visual science2025
Changes in Retinal Vasculature Phenotype and Choroidal Blood Flow at High Altitude in Healthy Lowlanders.
Article in Investigative ophthalmology & visual science, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
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Who cites it
3 citing papers in PubMed.
- Effect of chronic high-altitude hypoxia on retinal vascular phenotype, choroidal and retinal vasoreactivity in Peruvian highlanders.Experimental physiology · 2026Article
- Bridging Hypoxia and Vision Loss: The Emerging Role of Connexins in Local and Systemic Eye Diseases.International journal of molecular sciences · 2026Review
- The effect of high-altitude exposure on Vogt-Koyanagi-Harada syndrome: a case report.BMC ophthalmology · 2025Article
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Authors and funding
14 authors.
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No grant is acknowledged in the PubMed record.
Abstract
Purpose: The aim of this study was to characterize changes in retinal vessel diameters and choroidal blood flow in healthy lowlanders during a high-altitude expedition. Methods: Ocular examination, fundus images acquired using a handheld camera, and laser Doppler flowmetry (LDF) measurements within the subfoveal choroid (blood flow = ChBF, blood velocity = ChVel, and blood volume = ChVol) were carried out at 200 m and after 9 days at 5100 m in 11 healthy participants. Fundus images were analyzed with the semi-automatic software Vessel Assessment and Measurement Platform for Images of the Retina (VAMPIRE) version 3.2 to quantify retinal vessel parameters: the central retinal artery equivalent (CRAE), the central retinal vein equivalent (CRVE), and arterial and venular tortuosity. Hematocrit and hemoglobin concentrations were also measured at both altitudes. Results: Corneal thickness increased slightly at altitude (median = 536 µm, interquartile range = 25-75%: [521-571] at 200 m vs. 561 µm [540-574] at 5100 m, P = 0.004). No participant was affected by high-altitude retinopathy. From 200 m to 5100 m, ChVol and ChBF decreased significantly (-31% [43-22], P = 0.003 and -13% [22-8], P = 0.01, respectively), ChVel increased (+17% [10-44], P = 0.003), and CRVE (+10% [3-14], P = 0.04) and venular tortuosity (+142% [71-168], P = 0.04) increased significantly. The altitude-induced increase in hematocrit correlated negatively with the decrease in ChBF (r = -0.88, P < 0.001) and positively with the increase in CRVE (r = 0.88, P = 0.01). Conclusions: Acute high-altitude exposure leads to a decrease of ChBF (partly related to a decrease in blood volume) and an increase in retinal vein diameter and tortuosity. The physiological consequences of these changes on retinal blood flow and retinal function remain to be explored.
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