title: Alterations of retinal capillary blood flow in preclinical retinopathy in subjects with type 2 diabetes.
abstract: BACKGROUND
  To identify alterations of retinal capillary blood flow in the papillomacular area in preclinical diabetic retinopathy using the Heidelberg scanning laser Doppler flowmeter.
  
  
  METHODS
  Ten eyes from ten patients with type 2 diabetes and no lesions visible on fundus photography (level 10 of Wisconsin grading) and ten eyes from ten healthy subjects of similar age range were examined with the HRF. Intravisit reproducibility of retinal capillary blood flow measurements was assessed in normal subjects and in type 2 diabetic patients, comparing different measurement areas and different analysis procedures: (a) 10x10 pixel box with original software, (b) 10x10 pixel box with SLDF software, and (c) whole-scan analysis with SLDF software (automatic full-field perfusion image analysis).
  
  
  RESULTS
  Intravisit reproducibility for the whole-scan analysis in the papillomacular area was 3.52%, 4.81% and 4.60% for volume (VOL), flow (FLW) and velocity (VEL) respectively. Using this method, mean and SD values for retinal capillary blood-flow are 13.25+/-2.87, 214.58+/-55.30 and 0.74+/-0.17, for VOL, FLW and VEL for healthy eyes, comparing with 19.85+/-6.22, 360.87+/-158.70 and 1.20+/-0.48 in eyes with preclinical diabetic retinopathy (P<0.010, P<0.019 and P<0.015 respectively).
  
  
  CONCLUSIONS
  The HRF shows acceptable reproducibility when using whole-scan analysis in the papillomacular area. Retinal capillary blood VOL, FLW and VEL were particularly increased in five of the ten diabetic eyes examined, with values over the mean + 2SD of the control population, suggesting that eyes showing increased retinal capillary blood flow may indicate risk of progression.
authors.affiliation: Department of Ophthalmology, University Hospital of Coimbra, Portugal.
authors.forename: José
authors.initials: J
authors.lastname: Ludovico
authors.forename: Rui
authors.initials: R
authors.lastname: Bernardes
authors.forename: Isabel
authors.initials: I
authors.lastname: Pires
authors.forename: João
authors.initials: J
authors.lastname: Figueira
authors.forename: Conceição
authors.initials: C
authors.lastname: Lobo
authors.forename: José
authors.initials: J
authors.lastname: Cunha-Vaz
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002196:Capillaries / Q000502:physiology; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000502:physiology*