The long term objective of this proposal is twofold: a) Measure oxygen delivery from the retinal circulation to retinal tissue in the normal and diseased retina and determine whether and when this delivery becomes abnormal in the course of retinal vascular diseases such as diabetic retinopathy; b) Investigate whether oxygen diffusion through the arteriolar vessel wall and physiological shunting of oxygen plays a role in the regulation of oxygen delivery to retinal tissue. The first three years of this project will be devoted to accomplishing the following specific aims: A.1. Construction of the LDV-oximeter (LDO) and testing on whole blood flowing through tubes. This oximeter will be based on a new approach to reflection oximetry which stems from recent studies on the nature of light backscattered by red blood cells in retinal vessels. A.2. Measurements of oxygen saturation, blood flow oxygen delivery in anesthetized cats under various physiological conditions. A.3. Measurements in normal human volunteers. Establish reproducibility and sensitivity of the LDO technique. The technique proposed in this application represents a new approach to oximetry and may provide a simpler clinical tool for measuring oxygen saturation in retinal vessels than previous techniques. Furthermore, the LDO instrument may allow, for the first time, continuous measurement of oxygen delivery by the retinal circulation to the retinal tissue. It is hoped that this measurement will in the long term determine the role of oxygen delivery in the pathophysiology of vascular diseases such as diabetic retinopathy.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY008413-03
Application #
3265752
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1989-12-01
Project End
1992-11-30
Budget Start
1991-12-01
Budget End
1992-11-30
Support Year
3
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Presbyterian Medical Center of Phila
Department
Type
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Buerk, D G; Riva, C E; Cranstoun, S D (1996) Nitric oxide has a vasodilatory role in cat optic nerve head during flicker stimuli. Microvasc Res 52:13-26
Buerk, D G; Riva, C E; Cranstoun, S D (1995) Frequency and luminance-dependent blood flow and K+ ion changes during flicker stimuli in cat optic nerve head. Invest Ophthalmol Vis Sci 36:2216-27
Mendel, M J; Toi, V V; Riva, C E et al. (1993) Eye-tracking laser Doppler velocimeter stabilized in two dimensions: principle, design, and construction. J Opt Soc Am A 10:1663-9
Buerk, D G; Shonat, R D; Riva, C E et al. (1993) O2 gradients and countercurrent exchange in the cat vitreous humor near retinal arterioles and venules. Microvasc Res 45:134-48
Riva, C E; Harino, S; Petrig, B L et al. (1992) Laser Doppler flowmetry in the optic nerve. Exp Eye Res 55:499-506
Shonat, R D; Wilson, D F; Riva, C E et al. (1992) Effect of acute increases in intraocular pressure on intravascular optic nerve head oxygen tension in cats. Invest Ophthalmol Vis Sci 33:3174-80
Pournaras, C J; Shonat, R D; Munoz, J L et al. (1991) New ocular micromanipulator for measurements of retinal and vitreous physiologic parameters in the mammalian eye. Exp Eye Res 53:723-7
Riva, C E; Harino, S; Shonat, R D et al. (1991) Flicker evoked increase in optic nerve head blood flow in anesthetized cats. Neurosci Lett 128:291-6