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

Abstract

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.

New insights into refraction and intraocular pressure in simulated plateau environment

“…A previous study showed that IOP measured after 40 minutes of continuous blowing of − 19°C air into the subjects' eyes was signi cantly lower [9], so we also need to exclude the effect of temperature factors on IOP. Wu et al [10], in an experiment controlling for temperature stability with 20 volunteers, found that the mean IOP values after 7 days of continuous measurement from Beijing to Tibet (3658 m) were statistically signi cantly higher than the baseline, although the temperature remained stable during the 7 days on the plateau; however, this may have been related to the subjects' longer exposure time in the plateau environment and the signi cant increase in corneal thickness. In a study by Willmann et al [2], to ensure temperature stability and consider the effect of corneal thickness on IOP, subjects were exposed to 4559 m for 3 days, and signi cant changes in IOP were found after corneal thickness correction compared to baseline.…”

Influence of hypobaric hypoxic conditions on ocular structure and biological function at high attitudes: a narrative review

“…Conversely, Wu et al (2020) measured the IOP of 20 participants after 7 days at 3,658 m (Beijing to Tibet) and found the mean IOP was statistically higher than baseline. In addition, Najmanova et al (2018) studied IOP at 6,200 m for 4 and 10 min and found that the mean IOP increased by 1.2 mmHg and 0.9 mmHg, respectively, but returned to the baseline level when oxygen was restored.…”

A Review of Intraocular Pressure (IOP) and Axial Myopia

“…Moreover, the IOP level recovered and was accompanied by axial shortening after rest, thereby emphasizing the essentiality of measuring ocular rigidity in vivo in human eyes while detecting the IOP [ 83 ]. A study about the effects of high altitude on IOP and axial length found that a high altitude from Beijing to Lhasa led to a small but significant increase in IOP and axial length [ 84 ]. Exercise can also affect IOP and AL.…”