title: Relationship between macular microcirculation and progression of diabetic macular edema.
abstract: OBJECTIVE
  To investigate the relationship between blood flow velocity in perifoveal capillaries and retinal thickness at the central fovea in diabetic patients with clinically significant macular edema to elucidate the pathogenesis of diabetic macular edema.
  
  
  METHODS
  Comparative, cross-sectional, prospective study.
  
  
  METHODS
  Participants included diabetic patients with clinically significant macular edema (n = 22), matched diabetic patients without clinically significant macular edema (n = 22), and healthy volunteers (n = 16).
  
  
  METHODS
  Perifoveal capillary blood flow velocity was measured with fluorescein angiography using a scanning laser ophthalmoscope and was analyzed by the tracing method. The severity of perifoveal capillary abnormalities among diabetic patients without clinically significant macular edema was classified by the size and outline of the foveal avascular zone and extent of foveal capillary loss at the baseline by the use of fluorescein angiograms. Retinal thickness at the central fovea was measured by optical coherence tomography.
  
  
  METHODS
  Relationship between perifoveal capillary blood flow velocity and retinal thickness at the central fovea.
  
  
  RESULTS
  Perifoveal capillary blood flow velocity was significantly slower in the patients with clinically significant macular edema (0.94+/-0.09 mm/second) compared with the patients without clinically significant macular edema (1.22+/-0.20 mm/second) and the healthy volunteers (1.49+/-0.11 mm/second; P<0.0001). Capillary blood flow velocity negatively correlated with retinal thickness at the central fovea (r = -0.4018, P<0.0001). Capillary blood flow velocity varied among diabetic patients without clinically significant macular edema, and there were significant negative correlations between capillary blood flow velocity and the size of the foveal avascular zone (r = -0.52, P = 0.01), the outline of the foveal avascular zone (r = -0.44, P = 0.04), and the extent of foveal capillary loss (r = -0.51, P = 0.01).
  
  
  CONCLUSIONS
  The reduction of perifoveal capillary blood flow velocity may occur before the increase of retinal thickness at the central fovea in the diabetic patients. It is possible that long-term reduction of blood flow velocity increases retinal thickness of the macula and may play an important role in the development and the progression of diabetic macular edema.
authors.affiliation: Department of Ophthalmology, Tokyo Women's Medical University, Tokyo, Japan. sakata@oph.twmu.ac.jp
authors.forename: Kumi
authors.initials: K
authors.lastname: Sakata
authors.forename: Hideharu
authors.initials: H
authors.lastname: Funatsu
authors.forename: Seiyo
authors.initials: S
authors.lastname: Harino
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Noma
authors.forename: Sadao
authors.initials: S
authors.lastname: Hori
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D002196:Capillaries / Q000473:pathology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000503:physiopathology*; D018450:Disease Progression; D005451:Fluorescein Angiography; D005584:Fovea Centralis / Q000098:blood supply; D006801:Humans; D008266:Macula Lutea / Q000098:blood supply*; D008269:Macular Edema / Q000175:diagnosis / Q000503:physiopathology*; D008833:Microcirculation; D008875:Middle Aged; D009887:Ophthalmoscopy; D011446:Prospective Studies; D012160:Retina; D041623:Tomography, Optical Coherence