title: Wavelength dependence of the apparent diameter of retinal blood vessels.
abstract: Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column.
authors.affiliation: Department of Ophthalmology, University of Arizona, 655 North Alvernon Way, Tucson, Arizona 85721, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Park
authors.forename: Karen
authors.initials: K
authors.lastname: Twietmeyer
authors.forename: Russell
authors.initials: R
authors.lastname: Chipman
authors.forename: Neil
authors.initials: N
authors.lastname: Beaudry
authors.forename: David
authors.initials: D
authors.lastname: Salyer
mesh_terms: D000465:Algorithms; D000818:Animals; D005451:Fluorescein Angiography / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000166:cytology*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013053:Spectrophotometry / Q000379:methods*; D013552:Swine