May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Correlation between Po2 in Aqueous Humor and in Arterior Blood-non Invasive Measurement of Oxygen
Author Affiliations & Notes
  • T. Hiramitsu
    Photon Medical Research Ctr, Hamamatsu Univ Sch of Medicine, Hamamatsu, Japan
  • T. Suzuki
    Photon Medical Research Ctr, Hamamatsu Univ Sch of Medicine, Hamamatsu, Japan
  • K. Ohishi
    Photon Medical Research Ctr, Hamamatsu Univ Sch of Medicine, Hamamatsu, Japan
  • N. Yamaguchi
    Anesthesiology, Hamamatsu Univ Sch of Medicine, Hamamatsu, Japan
  • Footnotes
    Commercial Relationships  T. Hiramitsu, None; T. Suzuki, None; K. Ohishi, None; N. Yamaguchi, None.
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 3433. doi:
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      T. Hiramitsu, T. Suzuki, K. Ohishi, N. Yamaguchi; Correlation between Po2 in Aqueous Humor and in Arterior Blood-non Invasive Measurement of Oxygen . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3433.

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Abstract

Abstract: : Purpose: Many studies to investigate PO2 in the aqueous humor have been carried out. However, most of them have used a polarographic oxygen electrode for the measurement of PO2. As pointed out, this method has a great disadvantage of the inevitable loss of aqueous humor during the measurement. Recently we have succeeded in the non-invasive measurement of PO2 in the rabbit aqueous humor by using phosphorescence lifetime. In present study we examined the correlation between PO2 in the aqueous humor and PaO2 in the arterial blood. Methods: Oxymap® phosphorescence lifetime imaging system (Medical Systems Corp.) to measure the oxygen in the anterior chamber of the albino rabbits was used. This imaging system uses a gated, intensified CCD camera to image the phosphorescence, collecting a set of images at different times after the flash of excitation light. The phosphorescence decay calculation generates a map of phosphorescence lifetimes to produce a map of oxygen pressures using the Stern-Volmer relationship. After the solution of Pd-meso-(4-carboxyphenyl) porphyrin (Oxyophor R2) containing 25 mg/ml was subconjunctivally injected in bulbar conjuntiva of the normal rabbit eye, Oxygen maps on the anterior chamber were taken. The measurements were carried out without general anesthesia. For the experiments with greater than air oxygen in the inhaled gas, the oxygen was provided to the rabbit through the mask at different FiO2 values (93, 66, 42 and 21%). The rabbits were maintained for 1 hour at each value of the FiO2. PaO2 in the blood taken from the ear artery was measured periodically by a gas analyzer. Results: PO2 in the anterior chamber increased rapidly when the FiO2 was increased to 93% to levels about 3 times that of the control and then remained nearly constant through the hour that the FiO2 remained constant. The remarkable high increases of PaO2 during the high oxygen inhalation were well correlated with PO2 in the anterior chamber. PaO2 was maintained about 3 times as high as PO2 in the anterior chamber through the different oxygen inhalations. Conclusions: This study could reveal actually for the first time a well correlation between PO2 in the aqueous humor and PaO2 in the arterial blood which is theoretically reasonable. The non-invasive measurement of PO2 in the aqueous humor is very sensitive and can be a good weapon for the research.

Keywords: aqueous • anterior chamber • image processing 
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