Abstract

The oxygen tension in the vessels of the retina and optic nerve head has been measured noninvasively with a new phosphorescence imaging method. A phosphorescent oxygen-dependent probe, injected into the bloodstream of cats, was excited with a flash of light and the phosphorescence lifetime of the probe was measured. A simple Stern–Volmer relationship was used to convert lifetime to oxygen tension, and two-dimensional maps of intravascular oxygen tension were produced. We describe the equipment and the methodology for obtaining oxygen maps.

© 1992 Optical Society of America

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References

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  1. E. Stefánsson, “Oxygen and diabetic eye disease,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 120–123 (1990).
  2. V. A. Alder, S. J. Cringle, “Vitreal and retinal oxygenation,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 151–157 (1990).
  3. R. A. Linsenmeier, “Effects of light and darkness on oxygen distribution and consumption in the cat retina,” J. Gen. Physiol. 88, 521–542 (1986).
    [Crossref] [PubMed]
  4. C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).
  5. C. E. Riva, C. J. Pournaras, M. Tsacopoulos, “Regulation of local oxygen tension and blood flow in the inner retina during hyperoxia,” J. Appl. Physiol. 61, 592–598 (1986).
    [PubMed]
  6. D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
    [PubMed]
  7. J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).
  8. D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
    [PubMed]
  9. D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
    [PubMed]
  10. W. L. Rumsey, J. M. Vanderkooi, D. F. Wilson, “Imaging of phosphorescence: A novel method for measuring oxygen distribution in perfused tissue,” Science 241, 1649–1651 (1988).
    [Crossref] [PubMed]
  11. J. M. Vanderkooi, J. W. Berger, “Excited triplet states used to study biological macromolecules at room temperature,” Biochim. Biophys. Acta 976, 1–27 (1989).
    [Crossref] [PubMed]
  12. C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
    [Crossref] [PubMed]
  13. ANSI Z136.1 (American National Standards Institute, 1436 Broadway, New York, N.Y. 10018, 1986).
  14. F. C. Delori, O. Pomerantzeff, M. A. Mainster, “Light levels in ophthalmic diagnostic instruments,” in Ocular Effects of Non-ionizing Radiation, M. L. Wolbarsht, D. H. Sliney, eds., Proc. Soc. Photo-Opt. Instrum. Eng.229, 154–160 (1980).

1991 (2)

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
[Crossref] [PubMed]

1990 (3)

E. Stefánsson, “Oxygen and diabetic eye disease,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 120–123 (1990).

V. A. Alder, S. J. Cringle, “Vitreal and retinal oxygenation,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 151–157 (1990).

C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).

1989 (1)

J. M. Vanderkooi, J. W. Berger, “Excited triplet states used to study biological macromolecules at room temperature,” Biochim. Biophys. Acta 976, 1–27 (1989).
[Crossref] [PubMed]

1988 (2)

D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
[PubMed]

W. L. Rumsey, J. M. Vanderkooi, D. F. Wilson, “Imaging of phosphorescence: A novel method for measuring oxygen distribution in perfused tissue,” Science 241, 1649–1651 (1988).
[Crossref] [PubMed]

1987 (2)

J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

1986 (2)

C. E. Riva, C. J. Pournaras, M. Tsacopoulos, “Regulation of local oxygen tension and blood flow in the inner retina during hyperoxia,” J. Appl. Physiol. 61, 592–598 (1986).
[PubMed]

R. A. Linsenmeier, “Effects of light and darkness on oxygen distribution and consumption in the cat retina,” J. Gen. Physiol. 88, 521–542 (1986).
[Crossref] [PubMed]

Alder, V. A.

V. A. Alder, S. J. Cringle, “Vitreal and retinal oxygenation,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 151–157 (1990).

Berger, J. W.

J. M. Vanderkooi, J. W. Berger, “Excited triplet states used to study biological macromolecules at room temperature,” Biochim. Biophys. Acta 976, 1–27 (1989).
[Crossref] [PubMed]

Bloomgarden, D. C.

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

Cringle, S. J.

V. A. Alder, S. J. Cringle, “Vitreal and retinal oxygenation,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 151–157 (1990).

Defeo, S. P.

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

Delivoria-Papadopoulos, M.

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

Delori, F. C.

F. C. Delori, O. Pomerantzeff, M. A. Mainster, “Light levels in ophthalmic diagnostic instruments,” in Ocular Effects of Non-ionizing Radiation, M. L. Wolbarsht, D. H. Sliney, eds., Proc. Soc. Photo-Opt. Instrum. Eng.229, 154–160 (1980).

DiGiacomo, J. E.

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

Green, T. J.

D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
[PubMed]

J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

Harino, S.

C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
[Crossref] [PubMed]

Linsenmeier, R. A.

R. A. Linsenmeier, “Effects of light and darkness on oxygen distribution and consumption in the cat retina,” J. Gen. Physiol. 88, 521–542 (1986).
[Crossref] [PubMed]

Mainara, G.

J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).

Mainster, M. A.

F. C. Delori, O. Pomerantzeff, M. A. Mainster, “Light levels in ophthalmic diagnostic instruments,” in Ocular Effects of Non-ionizing Radiation, M. L. Wolbarsht, D. H. Sliney, eds., Proc. Soc. Photo-Opt. Instrum. Eng.229, 154–160 (1980).

Maniara, G.

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

Pastuszko, A.

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

Pawlowski, M.

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

Petrig, B. L.

C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
[Crossref] [PubMed]

Pomerantzeff, O.

F. C. Delori, O. Pomerantzeff, M. A. Mainster, “Light levels in ophthalmic diagnostic instruments,” in Ocular Effects of Non-ionizing Radiation, M. L. Wolbarsht, D. H. Sliney, eds., Proc. Soc. Photo-Opt. Instrum. Eng.229, 154–160 (1980).

Pournaras, C. J.

C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).

C. E. Riva, C. J. Pournaras, M. Tsacopoulos, “Regulation of local oxygen tension and blood flow in the inner retina during hyperoxia,” J. Appl. Physiol. 61, 592–598 (1986).
[PubMed]

Riva, C. E.

C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
[Crossref] [PubMed]

C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).

C. E. Riva, C. J. Pournaras, M. Tsacopoulos, “Regulation of local oxygen tension and blood flow in the inner retina during hyperoxia,” J. Appl. Physiol. 61, 592–598 (1986).
[PubMed]

Roth, A.

C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).

Rumsey, W. L.

D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
[PubMed]

W. L. Rumsey, J. M. Vanderkooi, D. F. Wilson, “Imaging of phosphorescence: A novel method for measuring oxygen distribution in perfused tissue,” Science 241, 1649–1651 (1988).
[Crossref] [PubMed]

Schneiderman, R.

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

Shonat, R. D.

C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
[Crossref] [PubMed]

Stefánsson, E.

E. Stefánsson, “Oxygen and diabetic eye disease,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 120–123 (1990).

Tsacopoulos, M.

C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).

C. E. Riva, C. J. Pournaras, M. Tsacopoulos, “Regulation of local oxygen tension and blood flow in the inner retina during hyperoxia,” J. Appl. Physiol. 61, 592–598 (1986).
[PubMed]

Vanderkooi, J. M.

J. M. Vanderkooi, J. W. Berger, “Excited triplet states used to study biological macromolecules at room temperature,” Biochim. Biophys. Acta 976, 1–27 (1989).
[Crossref] [PubMed]

W. L. Rumsey, J. M. Vanderkooi, D. F. Wilson, “Imaging of phosphorescence: A novel method for measuring oxygen distribution in perfused tissue,” Science 241, 1649–1651 (1988).
[Crossref] [PubMed]

D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
[PubMed]

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).

Wilson, D. F.

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
[PubMed]

W. L. Rumsey, J. M. Vanderkooi, D. F. Wilson, “Imaging of phosphorescence: A novel method for measuring oxygen distribution in perfused tissue,” Science 241, 1649–1651 (1988).
[Crossref] [PubMed]

J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

Adv. Exp. Med. Biol. (1)

D. F. Wilson, J. M. Vanderkooi, T. J. Green, G. Maniara, S. P. Defeo, D. C. Bloomgarden, “A versatile and sensitive method for measuring oxygen,” Adv. Exp. Med. Biol. 215, 71–77 (1987).
[PubMed]

Biochim. Biophys. Acta (1)

J. M. Vanderkooi, J. W. Berger, “Excited triplet states used to study biological macromolecules at room temperature,” Biochim. Biophys. Acta 976, 1–27 (1989).
[Crossref] [PubMed]

Graefe’s Arch. Clin. Exp. Ophthalmol. (3)

E. Stefánsson, “Oxygen and diabetic eye disease,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 120–123 (1990).

V. A. Alder, S. J. Cringle, “Vitreal and retinal oxygenation,” Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 151–157 (1990).

C. J. Pournaras, M. Tsacopoulos, C. E. Riva, A. Roth, “Diffusion of O2 in normal and ischemic retinas of anesthetized miniature pigs in normoxia and hyperoxia,” “Graefe’s Arch. Clin. Exp. Ophthalmol. 228, 138–142 (1990).

J. Appl. Physiol. (2)

C. E. Riva, C. J. Pournaras, M. Tsacopoulos, “Regulation of local oxygen tension and blood flow in the inner retina during hyperoxia,” J. Appl. Physiol. 61, 592–598 (1986).
[PubMed]

D. F. Wilson, A. Pastuszko, J. E. DiGiacomo, M. Pawlowski, R. Schneiderman, M. Delivoria-Papadopoulos, “Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets,” J. Appl. Physiol. 70, 2691–2696 (1991).
[PubMed]

J. Biol. Chem. (2)

J. M. Vanderkooi, G. Mainara, T. J. Green, D. F. Wilson, “An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence,” J. Biol. Chem. 252, 5476–5482 (1987).

D. F. Wilson, W. L. Rumsey, T. J. Green, J. M. Vanderkooi, “The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration,” J. Biol. Chem. 263, 2712–2718 (1988).
[PubMed]

J. Gen. Physiol. (1)

R. A. Linsenmeier, “Effects of light and darkness on oxygen distribution and consumption in the cat retina,” J. Gen. Physiol. 88, 521–542 (1986).
[Crossref] [PubMed]

Neurosci. Lett. (1)

C. E. Riva, S. Harino, R. D. Shonat, B. L. Petrig, “Flicker evoked increase in blood flow in the retina and optic nerve of anesthetized cats,” Neurosci. Lett. 128, 291–296 (1991).
[Crossref] [PubMed]

Science (1)

W. L. Rumsey, J. M. Vanderkooi, D. F. Wilson, “Imaging of phosphorescence: A novel method for measuring oxygen distribution in perfused tissue,” Science 241, 1649–1651 (1988).
[Crossref] [PubMed]

Other (2)

ANSI Z136.1 (American National Standards Institute, 1436 Broadway, New York, N.Y. 10018, 1986).

F. C. Delori, O. Pomerantzeff, M. A. Mainster, “Light levels in ophthalmic diagnostic instruments,” in Ocular Effects of Non-ionizing Radiation, M. L. Wolbarsht, D. H. Sliney, eds., Proc. Soc. Photo-Opt. Instrum. Eng.229, 154–160 (1980).

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Figures (7)

Fig. 1
Fig. 1

Excitation and emission spectra for Pd-mesotetra (4-carboxyphenyl) porphine bound to albumin. The probe was dissolved in dimethyl sulfoxide (DMSO) at 1–3 mg/mL, and a small amount was added to a medium containing 150 mM of NaCl, 0.5% bovine serum albumin, and 10 mM of glucose. The solution was treated with ~ 2–5 units of glucose oxidase, sealed in a glass vial, and placed in a Perkin-Elmer LS-5 spectrofluorometer. Light at the excitation peak (422 nm) was used for measuring the emission spectrum, and the 698-nm emission peak was used to measure the excitation spectrum. The spectra are uncorrected; a gate of 1 ms and a time delay of 0.5 ms were used.

Fig. 2
Fig. 2

Temperature and pH dependence of the Stern–Volmer quenching constant kQ and the lifetime at zero O20) for Pd-mesotetra (4-carboxyphenyl) porphine. The probe was dissolved (2-μM final concentration) in a medium containing 150 mM of NaCl, 20 mM of N-[2-hydroxyethyl]piperazine-N′ [2-ethanesulfonic acid] (HEPES), 1 mM of ethylenediaminetetraacetic acid (EDTA), 10 mM of glucose and 5–50 units of catalase/mL. The pH was adjusted to 6.43, 6.80, 7.22, or 7.75 with a Trisma base, and solutions at each pH were either placed in an open flask to equilibrate with air or treated with ~ 2–5 units of glucose oxidase and sealed in glass vials. The samples were placed in a Dubnoff shaking water bath and equilibrated at each of the indicated temperatures, and the phosphorescence lifetimes were measured. The temperature changes were carried out first as a sequence of increasing, then as a sequence of decreasing, temperatures. There was no systematic dependence on the order of the temperature changes, which indicates that temperature equilibrium was attained, and the measured lifetimes were averaged (n = 2). The kQ was calculated from the values found for τ0 and the lifetimes in the air-saturated medium by using the Stern–Volmer equation.

Fig. 3
Fig. 3

Phosphorescence imaging microscope. A filter block (shaded) inside the epifluorescence attachment holds the primary excitation filter, beam-splitting mirror, and the first suppression filter. The negative power contact lens is necessary for viewing the fundus with the microscope optics.

Fig. 4
Fig. 4

Phosphorescence decay curve. The individual data points were calculated by manually averaging the integrated intensity from a 10 × 10-pixel region in the center of the ONH for the images produced with protocol C. (The first six are shown in Fig. 5.) A single exponential least-squares fit to these points [when using Eq. (2)] is also shown. By generating the complete oxygen map, the computer works on each individual pixel element rather than on the small group indicated here, but the result is similar. For this particular fit τ is 94 ± 5 μs (mean ± standard deviation), and the pO2 is 27 ± 2 Torr. The data point associated with the 10-μs delay image demonstrates the effect of collecting images near the peak of the phosphorescence emission and excitation flash. Since peak phosphorescence emission occur slightly (1–2 μs) after peak flash excitation, the 10-μs delay image occasionally has an integrated intensity value that is lower than expected. This effect, however, is only seen occasionally and only minimally influences the fit.

Fig. 5
Fig. 5

Phosphorescence intensity images at different delay times. The first six integrated intensity images, which are photographed directly from the TV monitor, are shown at 10 μs (a), 20 μs (b), 30 μs (c), 40 μs (d), 60 μs (e), and 80 μs (f) for one measurement taken in normal physiological conditions by using a 10-point protocol with green flash excitation. The higher probe density in the ONH and venules permits the recognition of these anatomical features. A magnification of 20× was used (≈ 4 mm across the screen, 138 pixels/mm of fundus).

Fig. 6
Fig. 6

Oxygen map of the retina and ONH taken with green flash excitation by using procotol C. The gray-scale band across the top designates full-scale pO2 from 0 to 150 Torr (left to right). A magnification of 20× was used (≈ 4 mm across the screen; 138 pixels/mm).

Fig. 7
Fig. 7

Oxygen map of the retina and ONH taken with blue flash excitation by using protocol C. The gray-scale band across the top designates full-scale pO2 from 0 to 150 Torr (left to right). A magnification of 20× was used (≈ 4 mm across the screen; 138 pixels/mm).

Tables (3)

Tables Icon

Table I Filter Block Combinations and Flash Energy Density

Tables Icon

Table II Timing Protocols

Tables Icon

Table III Average pO2 in Different Regions from Figs. 6 and 7a

Equations (2)

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τ 0 τ = 1 + ( k Q ) ( τ 0 ) ( pO 2 ) ,
t d I ( t ) d t = t d I 0 exp ( - t / τ ) d t = I 0 τ exp ( - t d / τ ) ,

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