title: Spectral imaging technique for retinal perfusion detection using confocal scanning laser ophthalmoscopy.
abstract: To evaluate retinal perfusion in the human eye, a dual-wavelength confocal scanning laser ophthalmoscope (cSLO) was developed that provides spectral imaging of the fundus using a combination of red (670 nm) and near-infrared (810 nm) wavelengths. The image of the ocular fundus was analyzed to find out if quantitative measurements of the reflectivity of tissue permit assessment of the oxygen perfusion of tissue. We explored problems that affect the reproducibility of patient measurements such as non-uniformity errors on the image. For the first time, an image processing technique was designed and used to minimize the errors of oxygen saturation measurements by illumination correction in retina wide field by increasing SNR. Retinal images were taken from healthy and diabetic retinopathy eyes using the cSLO with a confocal aperture of 100 μm. The ratio image (RI) of red/IR, as oxygen saturation (SO2) index, was calculated for normal eyes. The image correction technique improved the reproducibility of the measurements. Average RI intensity variation of healthy retina tissue was determined within a range of about 5.5%. The capability of the new technique to discriminate oxygenation levels of retinal artery and vein was successfully demonstrated and showed good promise in the diagnosis of the perfused retina.
authors.affiliation: Tabriz University of Medical Sciences, School of Medicine, Department of Medical Physics, Tabriz 51666, Iran. s.h.rasta@abdn.ac.uk
authors.forename: Seyed Hossein
authors.initials: SH
authors.lastname: Rasta
authors.forename: Ayyakkannu
authors.initials: A
authors.lastname: Manivannan
authors.forename: Peter F
authors.initials: PF
authors.lastname: Sharp
mesh_terms: D006801:Humans; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D019721:Ophthalmoscopes; D009887:Ophthalmoscopy / Q000379:methods* / Q000706:statistics & numerical data; D055620:Optical Phenomena; D010100:Oxygen / Q000378:metabolism*; D012016:Reference Values; D015203:Reproducibility of Results; D012160:Retina / Q000033:anatomy & histology / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism
chemical_list: D010100:Oxygen