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Published on: July 23, 2016
INTRAOCULAR PRESSURE AND EYE HYDRODYNAMICS DURING BRIEF HEAD-DOWN TILT
Abstract:
Intraocular pressure (IOP) and eye hydrodynamics (aqueous outflow easiness rate (C) and moisture chamber production (F)) were studied in 9 adult volunteers subjected to the hypogravity effects of head-down tilt (HDT) at -15⁰ to the horizontal plane. The volunteers stayed in the horizontal and tilted positions for 10 minutes. IOP was measured according to Maklakov (tonometer 5 g), C and F - according to Nesterov (simplified tonography). In parallel, heart rate (HR) and systolic and diastolic blood pressures (SBP and DBP) were measured in the sitting, lying and tilted positions. In HDT IOP rose 10.3 % (p < 0.05) and C reduced 60 % (p < 0.05); F showed an uncertain trend down by 59 % (p > 0.05). Increase of the Bekker coefficient by 168 % (p < 0.05) could testify interconnection of the increased IOP and impaired moisture outflow. Moreover, in HDT DBP showed a rise while HR decreased. These results suggest that during brief tilt- down IOP increases not only because of a greater filling of the choroid vessels, but also because of retarded outflow of the intraocular fluid. The downward trend in fluid production can be a compensatory reaction to increased'IOP.
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