Optical coherence angiography

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Abstract

Noninvasive angiography is demonstrated for the in vivo human eye. Three-dimensional flow imaging has been performed with high-speed spectral-domain optical coherence tomography. Sample motion is compensated by two algorithms. Axial motion between adjacent A-lines within one OCT image is compensated by the Doppler shift due to bulk sample motion. Axial displacements between neighboring images are compensated by a correlation-based algorithm. Three-dimensional vasculature of ocular vessels has been visualized. By integrating volume sets of flow images, two-dimensional images of blood vessels are obtained. Retinal and choroidal blood vessel images are simultaneously obtained by separating the volume set into retinal part and choroidal parts. These are corresponding to fluorescein angiogram and indocyanine angiogram.

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Most cited references 35

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The impact of ocular blood flow in glaucoma.

Josef Flammer, Selim Orgül, Vital P. Costa … (2002)

Two principal theories for the pathogenesis of glaucomatous optic neuropathy (GON) have been described--a mechanical and a vascular theory. Both have been defended by various research groups over the past 150 years. According to the mechanical theory, increased intraocular pressure (IOP) causes stretching of the laminar beams and damage to retinal ganglion cell axons. The vascular theory of glaucoma considers GON as a consequence of insufficient blood supply due to either increased IOP or other risk factors reducing ocular blood flow (OBF). A number of conditions such as congenital glaucoma, angle-closure glaucoma or secondary glaucomas clearly show that increased IOP is sufficient to lead to GON. However, a number of observations such as the existence of normal-tension glaucoma cannot be satisfactorily explained by a pressure theory alone. Indeed, the vast majority of published studies dealing with blood flow report a reduced ocular perfusion in glaucoma patients compared with normal subjects. The fact that the reduction of OBF often precedes the damage and blood flow can also be reduced in other parts of the body of glaucoma patients, indicate that the hemodynamic alterations may at least partially be primary. The major cause of this reduction is not atherosclerosis, but rather a vascular dysregulation, leading to both low perfusion pressure and insufficient autoregulation. This in turn may lead to unstable ocular perfusion and thereby to ischemia and reperfusion damage. This review discusses the potential role of OBF in glaucoma and how a disturbance of OBF could increase the optic nerve's sensitivity to IOP.

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On the histogram as a density estimator:L 2 theory

David A Freedman, Persi Diaconis (1981)

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Adverse reactions due to indocyanine green.

Roderick J. Sorenson, E Gragoudas, Kristine M. Hope … (1994)

Although adverse reactions to indocyanine green (ICG) are known to occur, the dye has been used for more than 30 years in tests of cardiac and hepatic function, with a high level of safety. Improved digital video technology has renewed interest in the use of intravenous ICG in ophthalmic imaging. This report describes the authors' experience regarding the safety of ICG for digital angiography and their recommendations for its use in the ophthalmic setting. Digital ICG videoangiography was performed in 1226 consecutive patients, and 1923 ICG videoangiography tests were performed. A registry of adverse reactions to ICG was established. Criteria were used to define mild, moderate, and severe adverse reactions, and these data were recorded for every ICG study performed. There were three (0.15%) mild adverse reactions, four (0.2%) moderate reactions, and one (0.05%) severe adverse reaction. There were no deaths. This study documents the safety of intravenous ICG for use in ophthalmic videoangiography.