title: Oxygen Saturation of Retinal Vessels in All Stages of Diabetic Retinopathy and Correlation to Ultra-Wide Field Fluorescein Angiography.
abstract: OBJECTIVE
  The purpose of this study was to determine retinal hemoglobin oxygen saturation (SO2) in patients with diabetic retinopathy (DR) using retinal oximetry (RO) and to correlate the degree of retinal ischemia using intravenous fluorescein angiography (IVFA).
  
  
  METHODS
  This is a single-center cross-sectional cohort study. Twenty-seven controls and 60 adult patients with diabetes mellitus (16 without DR and 44 with DR) were enrolled. Patients were stratified according to DR severity. Using RO, SO2 was measured in major retinal arterioles (SaO2) and venules (SvO2). Using IVFA, the percentage of retinal ischemia in 31 patients with DR was calculated and correlated with RO.
  
  
  RESULTS
  Pairwise one-way analysis of variance (ANOVA) showed a significant increase in SaO2 and SvO2 in patients with proliferative DR (PDR) compared with controls (SaO2: PDR, 100 ± 7% vs. controls, 91 ± 4% [P = 0.003]; SvO2: PDR, 66 ± 11% vs. controls, 53 ± 6% [P < 0.00001]). The percentage of retinal ischemia also increased with DR severity: ANOVA showed a significant difference in retinal ischemia between all categories of nonproliferative DR vs. PDR: 2.31 ± 2% vs. 7.92 ± 9% (P = 0.017), respectively. Pearson two-tailed correlation showed significant correlation between SaO2 and ischemia (R = 0.467, P = 0.011).
  
  
  CONCLUSIONS
  Hemoglobin oxygen saturation of retinal arterioles and venules increases with DR severity; SaO2 correlates with increasing ischemia measured by IVFA. Retinal oximetry may complement current imaging strategies to noninvasively augment the diagnosis and risk stratification of patients with diabetes.
authors.affiliation: University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States.
authors.forename: Abhilash
authors.initials: A
authors.lastname: Guduru
authors.affiliation: University of North Carolina, Chapel Hill, North Carolina, United States.
authors.forename: Teresa G
authors.initials: TG
authors.lastname: Martz
authors.affiliation: University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States.
authors.forename: Alexa
authors.initials: A
authors.lastname: Waters
authors.affiliation: Division of Nephrology and Hypertension, University of North Carolina, Chapel Hill, North Carolina, United States.
authors.forename: Abhijit V
authors.initials: AV
authors.lastname: Kshirsagar
authors.affiliation: Department of Ophthalmology, University of North Carolina, Chapel Hill, North Carolina, United States.
authors.forename: Seema
authors.initials: S
authors.lastname: Garg
mesh_terms: D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D005451:Fluorescein Angiography / Q000379:methods*; D005654:Fundus Oculi; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D012171:Retinal Vessels / Q000473:pathology* / Q000503:physiopathology
chemical_list: D010100:Oxygen