title: Retinal blood flow is increased in type 1 diabetes mellitus patients with advanced stages of retinopathy.
abstract: BACKGROUND
  Diabetic retinopathy (DRP) is a common microvascular complication seen in patients with type 1 diabetes mellitus (T1DM). The effects of T1DM and concomitant (proliferative) DRP on retinal blood flow are currently unclear. Therefore, we measured retinal vascular blood flow in T1DM patients with and without DRP and non-diabetic controls. We further assessed the acute effects of panretinal photocoagulation on retinal microvascular bloodflow in eight patients with diabetes.
  
  
  METHODS
  Thirty-three T1DM patients with proliferative DRP, previously treated with panretinal photocoagulation (pDRP), 11 T1DM patients with untreated non-proliferative retinopathy (npDRP) and 32 T1DM patients without DRP (nDRP) were compared with 44 non-diabetic gender-matched controls. Using scanning laser Doppler flowmetry (HRF, Heidelberg) blood flow in the retinal microvasculature was measured temporal and nasal of the optic disc and averaged into one flow value per eye. The right eye was used as a default for further analyses. Eight patients with novel proliferative retinopathy (4 T1DM and 4 with type 2 diabetes) were measured before and several months after photocoagulation. Between-group differences in retinal blood flow were assessed using ANOVA corrected for multiple comparisons (Bonferroni).
  
  
  RESULTS
  Retinal blood flow was higher in the treated pDRP compared with the nDRP group and controls (all P Bonferroni < 0.01). Furthermore, there was a positive linear trend for blood flow with lowest blood flow in the control group and highest in the pDRP group (P-for-trend < 0.01). In the eight patients with novel proliferative retinopathy, blood flow did not significantly change before and after panretinal photocoagulation (P > 0.05). Using regression analysis, no variables were found as predictors of retinal blood flow.
  
  
  CONCLUSIONS
  In comparison with controls and nDRP patients, retinal blood flow significantly increased in the pDRP group, which previously underwent photocoagulation treatment, but not in the npDRP patients. These changes may be a consequence of a failing vascular autoregulation in advanced diabetic retinopathy.
authors.affiliation: Department of Ophthalmology, VU University Medical Center, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands. ht.nguyen@vumc.nl.
authors.forename: Hoang-Ton
authors.initials: HT
authors.lastname: Nguyen
authors.affiliation: Diabetes Center/Department of Internal Medicine and Department of Medical Psychology/Psychosocial Diabetology Section, VU University Medical Center, Amsterdam, The Netherlands.|Department of Psychology, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ, Brazil.
authors.forename: Eelco
authors.initials: E
authors.lastname: van Duinkerken
authors.affiliation: Department of Ophthalmology, Academic Medical Center, Amsterdam, The Netherlands.|Department of Ophthalmology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Frank D
authors.initials: FD
authors.lastname: Verbraak
authors.affiliation: Department of Ophthalmology, VU University Medical Center, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands.
authors.forename: Bettine C P
authors.initials: BC
authors.lastname: Polak
authors.affiliation: Department of Ophthalmology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ringens
authors.affiliation: Diabetes Center/Department of Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Michaela
authors.initials: M
authors.lastname: Diamant
authors.affiliation: Department of Ophthalmology, VU University Medical Center, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands.
authors.forename: Annette C
authors.initials: AC
authors.lastname: Moll
mesh_terms: D000328:Adult; D003922:Diabetes Mellitus, Type 1 / Q000150:complications*; D003930:Diabetic Retinopathy / Q000503:physiopathology* / Q000601:surgery; D018450:Disease Progression; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008028:Light Coagulation; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D012039:Regional Blood Flow
keywords: Diabetes; Diabetic retinopathy; Hemodynamics; Laser-doppler flowmetry