Hyperspectral imaging for measurement of oxygen saturation in the optic nerve head.

PURPOSE To evaluate a hyperspectral imaging technique for monitoring relative spatial changes in retinal oxygen saturation. METHODS The optic nerve head (ONH) and overlying vessels in cynomolgus monkey eyes were imaged with a fundus camera attached to a hyperspectral imaging system. Images were acquired with inspiration of room air and pure oxygen and at controlled intraocular pressures (IOP) of 15 mm Hg (normal) and 60 mm Hg (sustained for up to 5 minutes). Changes in relative blood oxygen saturation in the vessels and ONH were assessed from reflectance spectra. Saturation maps were derived from contributions of oxygenated and deoxygenated hemoglobin spectral signatures extracted from hyperspectral images. The results obtained with hyperspectral imaging were compared with known experimental outcomes. RESULTS Pure oxygen markedly increased oxygen saturation in veins. Increases in arteries and the ONH were smaller. The results obtained with hyperspectral image analysis agreed with known changes in oxygen saturation from breathing experiments. Raising IOP reduced saturation in all structures and resulted in profound desaturation of arteries. During sustained high IOP, a rebound in saturation was observed in the ONH. Spatial maps clearly showed the saturation changes in arteries, veins, and surrounding tissues. CONCLUSIONS Hyperspectral imaging can be adapted to measure and map relative oxygen saturation in retinal structures and the ONH in nonhuman primate eyes.

[1]  J. C. Ross,et al.  A Study of Retinal Venous Blood Oxygen Saturation in Human Subjects by Photographic Means , 1963, Circulation.

[2]  J. Hickam,et al.  Studies of the Retinal Circulation in Man: Observations on Vessel Diameter, Arteriovenous Oxygen Difference, and Mean Circulation Time , 1966, Circulation.

[3]  E. Stefánsson,et al.  Oxygenation and vasodilatation in relation to diabetic and other proliferative retinopathies. , 1983, Ophthalmic surgery.

[4]  R. Linsenmeier,et al.  Effects of light and darkness on oxygen distribution and consumption in the cat retina , 1986, The Journal of general physiology.

[5]  F. Delori.  Noninvasive technique for oximetry of blood in retinal vessels. , 1988, Applied optics.

[6]  J W Berger,et al.  Excited triplet states used to study biological macromolecules at room temperature. , 1989, Biochimica et biophysica acta.

[7]  F. Delori,et al.  Spectral reflectance of the human ocular fundus. , 1989, Applied optics.

[8]  B L Petrig,et al.  Rhythmic changes in velocity, volume, and flow of blood in the optic nerve head tissue. , 1990, Microvascular research.

[9]  C E Riva,et al.  Effect of acute increases in intraocular pressure on intravascular optic nerve head oxygen tension in cats. , 1992, Investigative ophthalmology & visual science.

[10]  A. Augustin,et al.  The influence of intraocular pressure and systemic oxygen tension on the intravascular pO2 of the pig retina as measured with phosphorescence imaging. , 1997, Survey of ophthalmology.

[11]  S. Hayreh.  Factors Influencing Blood Flow in the Optic Nerve Head , 1997, Journal of glaucoma.

[12]  C E Riva,et al.  Continuous measurements of intra-vascular pO2 in the pig optic nerve head. , 1997, Klinische Monatsblatter fur Augenheilkunde.

[13]  G A Cioffi,et al.  The vascular pattern of the optic nerve and its potential relevance in glaucoma , 1998, Current opinion in ophthalmology.

[14]  J S Tiedeman,et al.  Retinal oxygen consumption during hyperglycemia in patients with diabetes without retinopathy. , 1998, Ophthalmology.

[15]  C E Riva,et al.  Simultaneous tissue PO2, nitric oxide, and laser Doppler blood flow measurements during neuronal activation of optic nerve. , 1998, Advances in experimental medicine and biology.

[16]  E. Stefánsson,et al.  Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors. , 1999, Investigative ophthalmology & visual science.

[17]  G. Cioffi,et al.  The Effect of Chronic Ischemia on the Primate Optic Nerve , 1999, European journal of ophthalmology.

[18]  D. Schweitzer,et al.  In vivo measurement of the oxygen saturation of retinal vessels in healthy volunteers , 1999, IEEE Transactions on Biomedical Engineering.

[19]  G A Cioffi,et al.  Optic nerve blood flow in glaucoma. , 1999, Seminars in ophthalmology.

[20]  J. Beach,et al.  Oximetry of retinal vessels by dual-wavelength imaging: calibration and influence of pigmentation. , 1999, Journal of applied physiology.

[21]  M. H. Smith,et al.  Retinal imaging techniques in diabetes. , 2000, Diabetes technology & therapeutics.

[22]  Dietrich Schweitzer,et al.  A new method for the measurement of oxygen saturation at the human ocular fundus , 2001 .

[23]  L. Kagemann,et al.  Simultaneous management of blood flow and IOP in glaucoma. , 2001, Acta ophthalmologica Scandinavica.

[24]  Tatsuya Deguchi,et al.  Retinal oxygen saturation levels in patients with central retinal vein occlusion. , 2002, Ophthalmology.

[25]  C. Riva,et al.  Hemoglobin oxygen saturation (So2) in the human ocular fundus measured by reflectance oximetry: preliminary data in retinal veins. , 2002, Klinische Monatsblatter fur Augenheilkunde.