TY  - JOUR
PY  - 2014//
TI  - Acute hypoxic hypoxia and isocapnic hypoxia effects on oculometric features
JO  - Aviation, space, and environmental medicine
A1  - Stepanek, Jan
A1  - Pradhan, Gaurav N.
A1  - Cocco, Daniela
A1  - Smith, Benn E.
A1  - Bartlett, Jennifer
A1  - Studer, Marc
A1  - Kuhn, Fabian
A1  - Cevette, Michael J.
SP  - 700
EP  - 707
VL  - 85
IS  - 7
N2  - INTRODUCTION: Visual performance impairment after hypoxia is well recognized in military and civilian aviation. The aims of this study were: 1) to assess oculometric features such as blink metrics, pupillary dynamics, fixations, and saccades as cognitive indicators of early signs of hypoxia; and 2) to analyze the impact of different hypoxic conditions ["hypoxic hypoxia" (HH) and "isocapnic hypoxia" (IH)] on specified oculometrics during mental workloads. <br><br>METHODS: Oculometric data were collected on 25 subjects under 3 conditions: normoxia, HH (8% O2 + balance N2), and IH (7% O2 + 5% CO2 + balance N2). The mental workload task consisted of reading aloud linear arrays of numbers after exposure to gas mixtures. <br><br>RESULTS: Blink rates were significantly increased under hypoxic conditions (by +100.7% in HH and by +92.8% in IH compared to normoxia). A faster recovery of blink rate was observed in transitioning from IH (23.6% vs. 76.3%) to normoxia. The percentage change in pupil size fluctuation was increased under HH more than under IH (29% vs. 4.4%). Under HH average fixation time and target area size were significantly higher than under IH. Total saccadic times under hypoxic conditions were significantly increased compared with normoxia. <br><br>CONCLUSIONS: These results suggest that oculometric changes are indicators of hypoxia, which can be monitored using compact, portable, noninvasive eye-tracking devices in a cockpit analogous environment to detect hypoxia-induced physiological changes in aircrew. Comparative results between HH and IH support the potential role of carbon dioxide in augmenting cerebral perfusion and hence improved tissue oxygen delivery.<p />  <p>Language: en</p>
LA  - en
SN  - 0095-6562
UR  - http://dx.doi.org/
ID  - ref1
ER  -