Intraocular Pressure at High Altitude

Abstract Purpose:to study changes of the intraocular pressure at high altitude and to compare tonometric measurements and atmospheric pressure. The intraocular pressure (IOP) increase is one of the favourable factors in the apoptosis or death of the retinal nervous cells and is responsable for the progressive lost of the same cells. Methods:during the "Cho Oyu 2008" expedition, some tonometric readings were recorded to 13123 ft. at the main base campsat 21066 ft. Four climbers undergone an ophthalmic check-up and a retinal peripapillary fibers thickness study with laser scanning polarimeter (GDx VCC Zeiss) before the depart. During the expedition, tonometric measurements were taken using the handheld instrument Tono Pen Avia (Reichert). Upon returning from the expedition, the four mountain climbers once more underwent ophthalmic examination and a study of the nervous retinal peripapillary fibers using GDxVCC. The readings recorded were analyzed using a Test T. Data collection on web and data elaboration was managed by CoMed research. Results:compared with the readings recorded during the first examination, a rise in the pressure readings was observed during the expedition. The IOP increase proved to be directly proportional to the reduction of the atmospheric pressure. However, when the measurements were taken again a week after, at the same altitude, a fall in the IOP readings was observed with a decrease within original readings. Conclusions:the ascent to high altitude initially determines a IOP increase in healthy subjects. However, the rise in IOP does not appear to be permanent. After an initial adjustment period, IOP readings returned within normal parameters. GDx measurements taken before and after the expedition are already under observation.