The eye in extreme environments

Mekjavič, Polona Jaki; Tipton, Michael J.; Mekjavic, Igor B.

doi:10.1113/ep088594

Cited by 11 publications

(10 citation statements)

References 66 publications

(93 reference statements)

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“…Most commonly, these hypoxia-induced vision changes are not clinically important and are reversed within weeks upon return to normoxia. Similarly, vasodilation of retinal vessels is reversible when adequate oxygen availability is restored (Bosch et al, 2009;Jaki Mekjavic et al, 2021). Visual function tests were not performed in the present study, however, no apparent hypoxia-related effects on vision were observed or reported by the participants, most likely due to low levels of hypoxia.…”

Section: Discussionmentioning

confidence: 62%

“…Technological developments (chairlifts and cable cars) have made many highaltitude (≥3,000 m; please see Table 1) ski slopes easily accessible to all levels of skiers, including children (Meijer and Jean, 2008;Giesenhagen et al, 2019). At these altitudes, several environmental factors, such as cold, ultraviolet radiation, and hypoxia, may significantly impact not only physical performance (Cymerman et al, 1996;Jaki Mekjavic et al, 2021), but other physiological and psychological systems as well. Indeed, impairment of the aerobic performance, resulting from the lower partial pressure of oxygen (PO 2 ) at altitude (Wehrlin and Hallén, 2006), has been observed in both adults and children, with the magnitude of such being similar (Kriemler et al, 2016;Kapus et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…The ocular apparatus is a commonly affected system at altitude (Jaki Mekjavic et al, 2021). As a consequence of the retina's high oxygen demand as highly metabolically active tissue (Eshaq et al, 2014), adequate retinal oxygenation is essential for the maintenance of normal visual function.…”

Section: Introductionmentioning

confidence: 99%

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Retinal blood vessel diameters in children and adults exposed to a simulated altitude of 3,000 m

Mlinar

Debevec²,

Kapus³

et al. 2023

Front. Physiol.

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Introduction: Technological advances have made high-altitude ski slopes easily accessible to skiers of all ages. However, research on the effects of hypoxia experienced during excursions to such altitudes on physiological systems, including the ocular system, in children is scarce. Retinal vessels are embryologically of the same origin as vessels in the brain, and have similar anatomical and physiological characteristics. Thus, any hypoxia-related changes in the morphology of the former may reflect the status of the latter.Objective: To compare the effect of one-day hypoxic exposure, equivalent to the elevation of high-altitude ski resorts in North America and Europe (∼3,000 m), on retinal vessel diameter between adults and children.Methods: 11 adults (age: 40.1 ± 4.1 years) and 8 children (age: 9.3 ± 1.3 years) took part in the study. They spent 3 days at the Olympic Sports Centre Planica (Slovenia; altitude: 940 m). During days 1 and 2 they were exposed to normoxia (FiO2 = 0.209), and day 3 to normobaric hypoxia (FiO2 = 0.162 ± 0.03). Digital high-resolution retinal fundus photographs were obtained in normoxia (Day 2) and hypoxia (Day 3). Central retinal arteriolar equivalent (CRAE) and venular equivalents (CRVE) were determined using an Automated Retinal Image Analyser.Results: Central retinal arteriolar and venular equivalents increased with hypoxia in children (central retinal arteriolar equivalent: 105.32 ± 7.72 µm, hypoxia: 110.13 ± 7.16 µm, central retinal venular equivalent: normoxia: 123.39 ± 8.34 µm, hypoxia: 130.11 ± 8.54 µm) and adults (central retinal arteriolar equivalent: normoxia: 105.35 ± 10.67 µm, hypoxia: 110.77 ± 8.36 µm; central retinal venular equivalent: normoxia: 126.89 ± 7.24 µm, hypoxia: 132.03 ± 9.72 µm), with no main effect of group or group*condition interaction. A main effect of condition on central retinal arteriolar and venular equivalents was observed (central retinal arteriolar equivalent:normoxia: 105.34 ± 9.30 µm, hypoxia: 110.50 ± 7.67 µm, p < 0.001; central retinal venular equivalent: normoxia: 125.41 ± 7.70 µm, hypoxia: 131.22 ± 9.05 µm, p < 0.001).Conclusion: A 20-hour hypoxic exposure significantly increased central retinal arteriolar and venular equivalents in adults and children. These hypoxia-induced increases were not significantly different between the age groups, confirming that vasomotor sensitivity of the retinal vessels to acute hypoxia is comparable between adults and prepubertal children.

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Section: Discussionmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Retinal blood vessel diameters in children and adults exposed to a simulated altitude of 3,000 m

Mlinar

Debevec²,

Kapus³

et al. 2023

Front. Physiol.

Self Cite

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“…Extreme weather events (EWEs) (e.g., heatwaves and cold spells) were associated with high morbidity through a range of physiological mechanisms (Kephart et al 2022 ). Extreme heat and cold temperatures also affect the structure and function of the eye and vision (Jaki Mekjavic et al 2021 ). It is possible that extreme temperatures and continued exposure to air pollution place additional burdens on eye health.…”

Section: Introductionmentioning

confidence: 99%

Impacts of heatwaves and cold spells on glaucoma in rural China: a national cross-sectional study

Wang

Yang

et al. 2023

Environ Sci Pollut Res

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China faces increasing health risks from climate change. The structure and function of the eye and vision were affected by extreme heat and cold. The study aimed to evaluate the impacts of heatwaves and cold spells on glaucoma. A national cross-sectional study of the Rural Epidemiology for Glaucoma (REG-China) was conducted in ten provinces of China, and 36,081 adults aged 40 years or more were included. Glaucoma signs were assessed via a standard examination. A total of 15 heatwave definitions, based on intensity (95th to 99th percentiles of temperature distribution) and duration (≥2 days, 3 days, and 4 days), were used to quantify heatwave effects, and 6 cold spell definitions were defined based on threshold temperature percentile (5th and 10th) and duration (3 days, 5 days, and 9 days). Multivariable-adjusted logistic regression models paired with interaction analysis were performed to investigate the impacts of heatwaves and cold spells on glaucoma, and the dose-response relationships were assessed using a restricted cubic spline (RCS) model. Subgroup analysis was conducted stratified by gender, age, smoking status, occupation, and family history of glaucoma. The overall prevalence of glaucoma was 2.1% (95% CI 1.94–2.25%). Higher heatwaves were significantly correlated with higher OR of glaucoma, with the OR (95% CI) ranging from 1.014 (1.009, 1.018) to 1.090 (1.065, 1.115) by different definitions. Glaucoma was affected by heatwaves more strongly than by cold spells. The effects of both heatwaves and cold spells were higher in males than females and in smokers than nonsmokers. These results of the present study evoked the attention of prospective research to elucidate the relationship between extreme temperatures and eye diseases.

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“…One of the major, as yet unsolved, problems to be faced by those exposed to long periods of microgravity is the visual disturbances collectively known as space flight‐associated neuro‐ocular syndrome (SANS). Jaki Mekjavic and colleagues discuss this and many other areas in their comprehensive review of the eye in extreme environments (Jaki Mekjavic, Tipton, & Mekjavic, 2021). Planetary habitation is an important aspect of space research dealing with the impact of prolonged exposure to ambient conditions (reduced gravity and oxygen levels) that differ from those of Earth.…”

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confidence: 99%