Noninvasive assessment of retinal vascular oxygen content among normal and diabetic human subjects: a study using hyperspectral computed tomographic imaging spectroscopy

Retina. 2014 Sep;34(9):1854-60. doi: 10.1097/IAE.0000000000000146.

Abstract

Purpose: This pilot study was aimed to demonstrate the clinical feasibility of using hyperspectral computed tomographic spectroscopy to measure blood oxygen content in human retinal vessels.

Methods: All procedures were performed under a University of Southern California Institutional Review Board-approved protocol and after obtaining informed consent. Fifty-seven subjects with and without diabetic retinopathy were dilated for standard fundus photography. Fundus photographs and retinal vascular oxygen measurements (oximetry) were made using a custom-made hyperspectral computed tomographic imaging spectrometer coupled to a standard fundus camera. Oximetry measurements were made along arteries (Aox) and veins (Vox) within vessel segments that were 1 to 2 disk diameters from the optic disk.

Results: For all control subjects (n = 45), mean Aox and Vox were 93 ± 7% and 65 ± 5% (P = 0.001), respectively. For all diabetic subjects (n = 12), mean Aox and Vox were 90 ± 7% and 68 ± 5% (P = 0.001), respectively. In subjects with proliferative diabetic retinopathy, Aox was significantly lower, and Vox was significantly higher than other groups (85 ± 4% and 71 ± 4%, respectively; P = 0.04, analysis of variance). There was a highly significant difference in the arteriovenous difference between subjects with proliferative diabetic retinopathy and those in the control group (14 vs. 26%, P = 0.003).

Conclusion: Hyperspectral computed tomographic spectroscopy is a clinically feasible method for measurement and analysis of vascular oxygen content in retinal health and disease. This study uses the techniques relevant to oximetry; however, the breadth of spectral data available through this method may be applicable to study other anatomical and functional features of the retina in health and disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Glucose / metabolism
  • Diabetic Retinopathy / physiopathology*
  • Diagnostic Techniques, Ophthalmological*
  • Female
  • Fluorescein Angiography
  • Glycated Hemoglobin / metabolism
  • Healthy Volunteers
  • Humans
  • Male
  • Middle Aged
  • Oximetry / methods
  • Oxygen / blood*
  • Pilot Projects
  • Retinal Vessels / physiopathology*
  • Spectrum Analysis
  • Tomography, X-Ray Computed

Substances

  • Blood Glucose
  • Glycated Hemoglobin A
  • hemoglobin A1c protein, human
  • Oxygen