Saccadic velocity and pupillary reflexes during acclimatization to altitude (4300 m)

Allen Cymerman, Stephen R. Muza, Anne L. Friedlander, Charles S. Fulco, Paul B. Rock

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Introduction: Oculometrics have been shown to be responsive to acute hypoxemia. We investigated whether oculometrics could be used as an objective index of a hypoxic effect on the central nervous system (CNS) during altitude acclimatization. We hypothesized that oculomotor reflexes [pupil diameter (PD), constriction amplitude (CA), constriction latency (CL), and saccadic velocity (SV)] changed in concert with a select number of accepted acclimatization variables and that these changes correlated with the severity of acute mountain sickness (AMS). Methods: After sea-level, baseline (SLB) measurements were obtained, 18 men (19-33 yr) were transported to Pikes Peak, CO (4300 m), where they remained for 14 d. Periodic measurements (days 1-4, 6, 7, 9, 10, and 12) were made of PD, CA, CL, and SV in addition to heart rate (HR), pulse oximetry (SpO2), end-tidal PO2 and PCO2, 24-h urinary catecholamine concentrations, and AMS severity (environmental symptoms questionnaire, ESQ). Results: PD and CL decreased from SLB on days 1-4 and subsequently returned toward SLB; these changes paralleled changes in ventilatory and circulatory variables. CA decreased on days 1 and 2 and remained decreased for 12 d. SV increased over days 1-6 then returned toward SLB with continued exposure, similar to changes in urinary catecholamines. With acclimatization, CL correlated with HR and SpO2; SV correlated with PCO2, HR, and SpO2. AMS severity peaked during days 2-4, returned toward SLB over the next 10 d, and correlated only with CL (p = 0.045). Conclusions: Oculometrics can be used as an indicator of CNS hypoxia and altitude acclimatization, although there was no strong correlation with AMS severity.

Original languageEnglish
Pages (from-to)627-634
Number of pages8
JournalAviation Space and Environmental Medicine
Volume76
Issue number7 I
StatePublished - 1 Jul 2005

Keywords

  • Acute mountain sickness
  • Hypoxia
  • Light reflex
  • Oculometrics
  • Pupillometry

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