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Retinal vessel oximetry using sequential and 'snapshot' hyperspectral imaging
Author(s) -
MCNAUGHT A,
HARVEY A,
MUYO G,
MORDANT D,
ALLABOUD I,
RITCHIE P
Publication year - 2009
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2009.2466.x
Subject(s) - retinal , glaucoma , hyperspectral imaging , retina , ophthalmology , medicine , biomedical engineering , optics , artificial intelligence , computer science , physics
Purpose Use of sequential, and 'snapshot' hyperspectral imagers to measure oxygen saturation in retinal vessels in normals, and examples of eye disease, eg glaucoma, and retinovascular diseases. Validation of estimated oximetry values using a model eye. Methods A sequential hyperspectral imager was constructed using a fundus camera with built‐in liquid‐crystal tuneable filter. Images of normals,and ocular disease are presented. A novel 'snapshot' hyperspectral imager is also described: this produces images in a single exposure. Validation of both devices using an artificial eye with capillary tubes containing human blood of known oxygen saturation, placed in front of an 'artificial retina' is described. The image analysis used to detect retinal vessels, and generate oximetric values is detailed. Results Both the sequential, and 'snapshot' retinal imagers produced accurate estimations of retinal vessel oxygen saturation, when compared with the model eye. Imaging of a small group of glaucoma eyes showed abnormally elevated venous oxygen saturation. In proliferative diabetic retinopathy, abnormally elevated venular saturation was found in areas of capillary loss on FFA. In vein occlusion, elevated venous saturation was found in eyes with ischaemic FFAs. Conclusion Both the sequential and 'snapshot' hyperspectral imagers deliver useful oximetric maps of the retina. The 'snapshot' device allows more rapid imaging. The elevated venular oxygen saturation seen in both glaucoma, and retinovascular disease, is perhaps evidence of reduced oxygen consumption in damaged inner retina in glaucoma, and/or vascular 'shunting' in retinovascular disease.