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      Intraocular pressure and axial length changes during altitude acclimatization from Beijing to Lhasa

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      Author(s): 1 , 2 , 2 , 1 , *
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      Publication date (Electronic):
      Journal: PLoS ONE
      Publisher: Public Library of Science

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          Abstract

          Purpose

          To investigate changes in intraocular pressure (IOP) and axial length (AL) on the ascent to high altitude from Beijing to Lhasa.

          Patients and methods

          Twenty volunteers (17 men, 3 women) who had been sent to work in Lhasa, Tibet for more than 6 months were enrolled. One of their journeys from Beijing to Lhasa was chosen as the time for the examination. IOP, AL, corneal curvature (K), and blood pressure (BP) were measured in Beijing (altitude 43 m) and Lhasa (altitude 3658 m). Their first examination was conducted at least 1 day before arriving in Lhasa and the second examination after they had stayed in Lhasa for 7 days. The data from the highland and lowland examinations were analyzed with a paired-sample T test and Pearson’s correlation coefficient was calculated for the association between IOP and average BP.

          Results

          The mean IOP was 12.65±2.34 mmHg in Beijing and 14.85±3.1 mmHg in Lhasa. The mean AL was 24.61±1.50mm in Beijing, and 24.98±1.45 mm in Lhasa. The IOP and AL showed a significant elevation in highland compared with lowland ( P<0.05). The mean K was 43.58±2.25 D in Beijing and 43.56±2.21 D in Lhasa and no significant difference was found in this study (P>0.05). A positive correlation between variance of IOP and ACD was found (r = 0.475, P<0.05) and no correlation between IOP and average BP was noted.

          Conclusions

          High altitude may lead to a small but significant change in IOP and axial length. However, the shape of the corneal surface was not influenced by the hypobaric and hypoxic conditions.

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          Most cited references20

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          New insights into ocular blood flow at very high altitudes.

          Frederic Truffer, Marco Maggiorini, Jacqueline Pichler Hefti … (2009)
          Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.
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            Exercise training reduces intraocular pressure among subjects suspected of having glaucoma.

            D Elliot, Tony Goldberg, Klaas van Gisbergen … (1991)
            The effect of exercise conditioning on elevated intraocular pressure has not been previously described among sedentary individuals. We prospectively observed intraocular pressure for nine sedentary subjects suspected of having glaucoma before and after 3 months of aerobic exercise training. Mean (+/- SEM) aerobic capacity, as assessed by maximal oxygen uptake, increased 6.3 +/- 1.6 mL.kg-1.min-1 (30%) (P less than .02). Mean intraocular pressure decreased 4.6 +/- 0.4 mmHg (20%) (P less than .001) at the end of the conditioning period. With cessation of exercise and subsequent detraining, intraocular pressure returned to elevated preconditioning levels by 3 weeks. Regular aerobic exercise is associated with a reduction in elevated intraocular pressure and may represent an effective nonpharmacologic intervention for patients suspected of having glaucoma.
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              What happens to intraocular pressure at high altitude?

              Peter A. Aspinall, E A Somner, Baljean Dhillon … (2007)
              To investigate changes of intraocular pressure on ascent to high altitude. The Apex 2 medical research expedition provided the opportunity to measure intraocular pressure (IOP) and central corneal thickness (CCT) in 76 healthy lowlanders. They all arrived in La Paz, Bolivia (altitude, 3700 m), where they spent 4 days before being driven more than 2 hours to the Cosmic Physics Laboratory at Chacaltaya (5200 m) where they stayed for 7 days. IOP and CCT were measured with a hand-held tonometer and ultrasound pachymetry on the first, third, and seventh days at 5200 m. Pre- and postexpedition CCT and postexpedition IOP readings at sea-level were also measured. IOP increased significantly from baseline after acute exposure to altitude before returning to baseline with time. IOP at baseline, change in IOP from baseline, and IOP at altitude did not predict symptoms of acute mountain sickness (AMS) or development of high-altitude retinopathy (HAR). Acute exposure to altitude caused a statistically significant but clinically insignificant increase in IOP. This finding may be partially explained by the change in CCT. IOP returned to baseline levels and possibly lower with prolonged exposure to altitude. Changes in IOP at altitude are not predictive of symptoms of acute mountain sickness (AMS) or development of high-altitude retinopathy (HAR).
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                Author and article information

                Contributors
                Yuan Wu:
                ORCID: http://orcid.org/0000-0003-2080-1414
                Role: ConceptualizationRole: InvestigationRole: MethodologyRole: Writing – original draftRole: Writing – review & editing
                Ci Ren Qiong Da: Role: Data curation
                Jiang Liu: Role: Data curation
                Xiaoming Yan:
                ORCID: http://orcid.org/0000-0001-7112-4420
                Role: Conceptualization
                Sanjoy Bhattacharya: Role: Editor
                Journal
                Journal ID (nlm-ta): PLoS One
                Journal ID (iso-abbrev): PLoS ONE
                Journal ID (publisher-id): plos
                Journal ID (pmc): plosone
                Title: PLoS ONE
                Publisher: Public Library of Science (San Francisco, CA USA )
                ISSN (Electronic): 1932-6203
                Publication date (Electronic): 29 January 2020
                Publication date Collection: 2020
                Volume: 15
                Issue: 1
                Electronic Location Identifier: e0228267
                Affiliations
                [1 ] Department of Ophthalmology, Peking University First Hospital, Beijing, China
                [2 ] Department of Ophthalmology, Tibet Autonomous Region People’s Hospital, Lhasa, Tibet Autonomous Region, China
                Bascom Palmer Eye Institute, UNITED STATES
                Author notes

                Competing Interests: The authors have declared that no competing interests exit.

                Author information
                http://orcid.org/0000-0003-2080-1414
                http://orcid.org/0000-0001-7112-4420
                Article
                Publisher ID: PONE-D-19-20504
                DOI: 10.1371/journal.pone.0228267
                PMC ID: 6988913
                PubMed ID: 31995608
                SO-VID: 27b7293c-b142-41c5-9b2f-5c148ff23b34
                Copyright © © 2020 Wu et al
                License:

                This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                History
                Date received : 20 July 2019
                Date accepted : 12 January 2020
                Page count
                Figures: 1, Tables: 3, Pages: 8
                Funding
                Funded by: Natural Science Foundation of Tibet Autonomous Region
                Award ID: XZ2017ZR-ZY032
                Award Recipient :
                ORCID: http://orcid.org/0000-0003-2080-1414
                This work was supported by the'Natural Science Foundation of Tibet Autonomous Region (NO XZ2017ZR-ZY032). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Categories
                Subject: Research Article
                Subject: Biology and Life Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Ocular Anatomy
                Subject: Cornea
                Subject: Medicine and Health Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Ocular Anatomy
                Subject: Cornea
                Subject: Medicine and Health Sciences
                Subject: Vascular Medicine
                Subject: Blood Pressure
                Subject: Biology and Life Sciences
                Subject: Anatomy
                Subject: Head
                Subject: Eyes
                Subject: Medicine and Health Sciences
                Subject: Anatomy
                Subject: Head
                Subject: Eyes
                Subject: Biology and Life Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Eyes
                Subject: Medicine and Health Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Eyes
                Subject: Biology and Life Sciences
                Subject: Cell Biology
                Subject: Hypoxia
                Subject: Biology and Life Sciences
                Subject: Physiology
                Subject: Biological Locomotion
                Subject: Climbing
                Subject: Medicine and Health Sciences
                Subject: Physiology
                Subject: Biological Locomotion
                Subject: Climbing
                Subject: Biology and Life Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Intraocular Pressure
                Subject: Medicine and Health Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Intraocular Pressure
                Subject: Research and Analysis Methods
                Subject: Computational Techniques
                Subject: Biometrics
                Subject: Biology and Life Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Ocular Anatomy
                Subject: Eye Lens
                Subject: Medicine and Health Sciences
                Subject: Anatomy
                Subject: Ocular System
                Subject: Ocular Anatomy
                Subject: Eye Lens
                Custom metadata
                Data Availability All relevant data are within the manuscript and its Supporting Information files.

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                ScienceOpen disciplines: Uncategorized

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