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T. Russomano* L. F. B. Chotgues* O. A. Lima de Sá* M. A. dos Santos* J. Ernsting**

Intra-ocular and Venous Pressures during Head-down Tilt. T. Russomano* L. F. B. Chotgues* O. A. Lima de Sá* M. A. dos Santos* J. Ernsting**. *Microgravity Laboratory-Brazil / ** King’s College London-UK. Objectives.

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T. Russomano* L. F. B. Chotgues* O. A. Lima de Sá* M. A. dos Santos* J. Ernsting**

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  1. Intra-ocular and Venous Pressures during Head-down Tilt T. Russomano* L. F. B. Chotgues* O. A. Lima de Sá* M. A. dos Santos* J. Ernsting** *Microgravity Laboratory-Brazil / ** King’s College London-UK

  2. Objectives 1) To determine the relationship between IOP and forehead venous pressure produced by 15 min exposures to: 0° (supine position), 17° HDT and 34° HDT 2) To compare the results obtained with HDT with the ones found in microgravity 3) To discuss the physiological mechanisms involved in the increase of IOP and venous pressures with HDT and in microgravity

  3. Physiology of the eye on Earth

  4. Physiology of the eye on Earth

  5. Physiology of the eye on Earth

  6. IOP in Microgravity 1st German-Russian MIR mission 1992 : 92% IOP rise Schwartz R, Draeger J, Groenhoff S, Flade K D Ophthalmologe 1993; 90: 640-2 2nd German D-2 Spacelab-Mission 1993: 114% IOP rise Draeger J, Schwartz R, Groenhoff S, Stern C Ophthalmologe 1994; 91: 697-9

  7. IOP - Parabolic Flight IOP increased 58% (19 mmHg) during parabolic flight (20 s of µG) compared to baseline values (12 mmHg) (n =11) Mader TH et al., Am J Ophtalmol. 1993 Mar 15; 115(3):347-50

  8. Method 0° (control) 17° HDT 34° HDT 0° (recovery) 15 min15 min15 min15 min VP VP VP VP IOP IOP IOP IOP IOP = intra-ocular pressure VP = forehead venous pressure

  9. Material

  10. Material

  11. Results

  12. Results

  13. Results IOP Venous Pressure (mmHg) (n=8) (mmHg) (n=4) Mean ± SE Mean Supine 14.7 ± 0.5 5.2 17° HDT 20.7 ± 0.6 13.0 34° HDT 25.5 ± 0.3 19.3 Supine 13.5 ± 0.8 4.0

  14. Expected Forehead Venous Pressure 17° HDT = approximately 13.0 mmHg 6.0 mmHg(Hydrostatic Pressure) 7.0 mmHg(Venous Pressure) Our result: 13.0 mmHg 34° HDT = approximately 19.0 mmHg 12.0 mmHg (Hydrostatic Pressure) 7.0 mmHg (Venous Presssure) Our result: 19.3 mmHg

  15. Central venous pressure in spaceBuckey J. C. et al, 1996

  16. Conclusion • IOP and forehead venous pressures simultaneously increased during HDT (r=0.99) regardless the angle of tilt employed and both returned to their control values in the supine position.

  17. Future Studies • Measurements of peripheral venous pressure of the forehead in microgravity should be made to clarify the mechanisms involved in the rise of IOP, which may differ from those found during HDT

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