The relation between intraocular pressure change and plasma natriuretic peptide under simulated hypobaric conditions.
OBJECTIVE
To ascertain whether the changes in intraocular pressure (IOP) that occur during hypobaric hypoxic exposure are related to plasma N-terminal pro-brain natriuretic peptide (BNP) levels.


METHODS
The study group comprised 26 healthy participants (all male, mean age 23.1 years). IOP was measured at local ground level, (792 m above sea level), then while in a chamber providing hypobaric hypoxic conditions (the subjects were exposed to a pressure equivalent to 9144 m for 1-3 min), and again after exit from the chamber. In each condition, the mean of three consecutive measurements of IOP was calculated for each eye. For BNP measurements, blood samples were drawn before the participants entered the chamber and just after they left the chamber.


RESULTS
IOP during hypobaric hypoxic exposure (18.00 +/- 3.70 mmHg) was significantly greater than that before (15.66 +/- 2.10 mmHg, P < 0.001) or after (16.10 +/- 2.63 mmHg, P = 0.001) the exposure. IOP levels before and after the exposure were not significantly different (P = 0.136). Plasma BNP levels measured before and after exposure to hypobaric hypoxic conditions were not significantly different (P = 0.462).


CONCLUSIONS
Plasma BNP levels did not change after short-term hypobaric hypoxic exposure, while the IOP increased. This increase may have been caused by some other systemic factors. As the hypobaric hypoxic conditions were reversed, IOP decreased to normal levels.
Karadag
Remzi
R
Department of Ophthalmology, Eskisehir Military Hospital, Eskisehir, Turkey.
Sen
Ahmet
A
Yildirim
Nilgun
N
Basmak
Hikmet
H
Golemez
Haydar
H
Cakir
Erdinc
E
Akin
Ahmet
A
D000328:Adult; D000531:Altitude; D001274:Atmospheric Pressure; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D007429:Intraocular Pressure; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D055815:Young Adult
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain