Optic nerve sheath diameter changes at high altitude and in acute mountain sickness: meta-regression analyses

Tsai, Tou-Yuan; Gozari, George; Su, Yung-Cheng; Lee, Yi-Kung; Tu, Yu–Kang

doi:10.1136/bjophthalmol-2020-317717

Cited by 4 publications

(4 citation statements)

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“…The meta-analysis revealed that apart from all these factors, the altitude of the place where the measurement was made and the individual patient characteristics also affected the ONSD measurement values. A previous study reported that the ONSD measurement increased by 0.14 mm for every 1000-m increase in altitude [35]. The hospital where our study was conducted and the CT images were obtained is located at an altitude of 8 m (26 ft).…”

Section: Resultsmentioning

confidence: 99%

Variability of the optic nerve sheath diameter on brain computed tomography in Turkish children based on sex and age

et al. 2023

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Background: Optic nerve sheath diameter (ONSD) measurement is a noninvasive method that can be used for intracranial pressure monitoring. Several studies have investigated normal ONSD values in children, but no general consensus has been reached yet.Objectives: The aim of our study was to reveal normal ONSD, eyeball transverse diameter (ETD), and ONSD/ETD values on brain Computed tomography (CT) in healthy children aged 1 month to 18 years. Methods: Children admitted to the emergency department with minor head trauma and had normal brain CT were included in the study. The demographic characteristics of the patients (age and sex) were recorded, and the patients were divided into four age groups: 1 month to 2 years, 2 to 4 years, 4 to 10 years, and 10 to 18 years.Results: The images of 332 patients were analyzed. When the median values of all measurement parameters (right and left ONSD, ETD, and ONSD/ETD) were compared between the right and left eyes, no statistically signi cant differences. When the same parameters were compared according to age group, the ONSD and ETD values differed signi cantly (values of males were found to be higher), but the ONSD proximal/ETD and ONSD middle/ETD values did not differ signi cantly.Conclusion: In our study, normal ONSD, ETD, and ONSD/ETD values were determined according to age and sex in healthy children. As the ONSD/ETD index did not statistically signi cantly differ according to age and sex, diagnostic studies for traumatic brain injuries can be performed using the index.

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Section: Resultsmentioning

confidence: 99%

Variability of the optic nerve sheath diameter on brain computed tomography in Turkish children based on sex and age

et al. 2023

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“…It is possible that the results of this study were affected by the altitude at which the city is located (2640 masl), since it has been shown that the value of the ONSD can increase by 0.14 mm per 1000 m of altitude and that adaptations can be seen within less than 1 week [ 17 , 19 , 20 ]. Higher ONSD values are thought to be due to increased cerebral vessel permeability at high altitudes that is not necessarily related to hICP [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

“…The objective of this study is to describe the pattern of normal values of the ONSD in a healthy adult population from the city of Bogotá, Colombia, at 2640 masl [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Optic nerve sheath diameter at high altitude: standardized measures in healthy volunteers

2022

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Background Increases in the diameter of the optic nerve sheath (ONSD) on ultrasound are associated with high intracranial pressure (hICP). The normal value varies with altitude and the population studied. The objective of this study is to describe the normal values of the ONSD in a healthy adult population of the city of Bogotá, Colombia, at 2640 meters above sea level (masl). Patients and methods A prospective observational study was conducted on a total of 247 healthy individuals recruited from May 2021 to May 2022 who were subjected to the color, low power, optic disk, safety, elevated frequency, dual (CLOSED) protocol for measuring the bilateral ONSD adjusted to the eyeball transverse diameter (ETD). Results A total of 230 individuals were analyzed; the average ONSD of the right eye (RE) was 0.449 cm (range 0.288–0.7) and that of the left eye (LE) was 0.454 cm (range 0.285–0.698); the correlation between RE and LE was 0.93 (p < 0.005), and the correlation of the ONSD/ETD ratios for the RE and LE was lower (r2 = 0.79, p < 0.005). A total of 10.8% of the studied population had values greater than 0.55 cm. Conclusions The median ONSD and ONSD/ETD ratio in the city of Bogotá are similar to those described in other populations; however, approximately 10.8% of the healthy population may present higher values, which would limit the use of ONSD on its own for clinical decision-making, only repeated measurements with significant changes in the ONSD and ONSD/ETD or asymmetries between the measurements of both eyes linked to clinical findings would allow the diagnosis of hICP.

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“…The results showed a statistically significant difference in ONSD between participants with and without AMS. However, the heterogeneity among the included studies was high (Tsai et al, 2022). To date, no study has compared participants with and without high myopia (HM) at high altitudes.…”

Section: Introductionmentioning

confidence: 99%

High myopia at high altitudes

Wang,

Huang,

Hsu

et al. 2024

Front. Physiol.

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Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS.Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain.Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS (rpb = 0.448, p = 0.019) and the presence of headache symptoms (rpb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms.Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

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Optic nerve sheath diameter changes at high altitude and in acute mountain sickness: meta-regression analyses

Cited by 4 publications

References 31 publications

Variability of the optic nerve sheath diameter on brain computed tomography in Turkish children based on sex and age

Variability of the optic nerve sheath diameter on brain computed tomography in Turkish children based on sex and age

Optic nerve sheath diameter at high altitude: standardized measures in healthy volunteers

High myopia at high altitudes

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