title: Retinal circulatory abnormalities in type 1 diabetes.
abstract: OBJECTIVE
  To quantify retinal circulatory abnormalities in patients with type 1 diabetes; to 1 diabetes; to compare blood speed and blood flow in major temporal retinal arteries as well as total retinal arterial cross-section measured in patients to that measured in controls without diabetes; to determine which factors are related to the measured abnormalities within the patient group.
  
  
  METHODS
  The laser Doppler technique and monochromatic fundus photography were used to measure retinal circulatory parameters in 39 patients with type 1 diabetes with duration of diabetes between 7 and 20 years and 13 age-matched controls without diabetes. Blood pressure, intraocular pressure, and heart rate were measured in all subjects. Glycosylated hemoglobin was measured in the patients. Retinopathy was assessed using standardized color fundus photography and fluorescein angiography.
  
  
  RESULTS
  Total retinal arterial cross-section was, on average, 17% higher (P = 0.007) in the patients than in the controls, and it increased with increasing duration of diabetes (P = 0.006). Arterial blood speed was, on average, 33% lower (P = 0.0001) in the patients than in the controls, and it decreased with increasing duration of diabetes (P = 0.03).
  
  
  CONCLUSIONS
  The retinal circulation of patients with type 1 diabetes with no retinopathy or background retinopathy is characterized by dilated major arteries with reduced blood speeds. Dilation of the larger retinal arteries, with the accompanying decrease in vascular resistance to flow in those vessels, appears to counteract an increase in resistance to flow at the level of the smaller retinal vessels.
authors.affiliation: Schepens Eye Research Institute, Boston, MA 02114.
authors.forename: G T
authors.initials: GT
authors.lastname: Feke
authors.forename: S M
authors.initials: SM
authors.lastname: Buzney
authors.forename: H
authors.initials: H
authors.lastname: Ogasawara
authors.forename: N
authors.initials: N
authors.lastname: Fujio
authors.forename: D G
authors.initials: DG
authors.lastname: Goger
authors.forename: N P
authors.initials: NP
authors.lastname: Spack
authors.forename: K H
authors.initials: KH
authors.lastname: Gabbay
mesh_terms: D000328:Adult; D001775:Blood Circulation / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology; D012161:Retinal Artery / Q000502:physiology*