Abstract
Purpose :
To determine retinal nerve fiber layer(RNFL) thickness and ridial peripapillary capillary(RPC) density changes in healthy subjects after 3-hour exposure to 4500m simulated altitude in a hypobaric chamber.
Methods :
RNFL thickness and RPC density(RPC-CD) measured by optical coherence tomography angiography (OCTA)were performed on 16 healthy subjects(32eyes) with mean age of 27 years. Measurements were obtained at ground level (44 m above sea level, Beijing,pre-hypobaric) and after 3-hour exposure to 4500m simulated altitude in a hypobaric chamber(post-hypobaric).Results were compared between pre-hypobaric and post-hypobaric to determine the effect of 3-hour exposure to decreased barometric pressure.
Results :
Following exposure to simulated high altitude, there was a significant increase in RPC capillary density in the inside disc(51.42 ±6.73&52.68±6.08,p=0.037)and nasal quadrant of optic disc(58.03±4.01&59.18±3.16,p=0.022).Meanwhile, increased RNFL thickness in the nasal quadrant of the optic disk (73.16±7.70) was showed compared with pre-hypobaric examination (69.8±8.22) (p=0.009).Rim area was significantly higher in post-hypobaric examination(1.47±0.40) than in baseline examination (1.43±0.40) (p=0.000),while s significant decrease in C/D was also observed(0.17±0.13&0.14±0.11,p=0.001).
Conclusions :
Exposure to simulated 4500m caused increased RNFL thickness , ridial peripapillary capillary density and rim area while decreased C/D in healthy subjects. These parameters might be a double-edged sword for optic nerve and sensitive parameters in physiologic acclimatization.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.