title: Diabetic macular ischaemia is associated with narrower retinal arterioles in patients with type 2 diabetes.
abstract: OBJECTIVE
  Diabetic macular ischaemia (DMI) is an important cause of visual loss in patients with diabetes, but its relationship to the larger retinal vessels is unknown. We examined whether retinal vessel calibre is related to DMI.
  
  
  METHODS
  Clinic-based case-control study of patients with type 2 diabetes. The presence and severity of DMI was assessed using Early Treatment Diabetic Retinopathy Study (ETDRS) protocols from fundus fluorescein angiographic (FFA) images. Custom software was used to quantify the greatest linear dimension and area of the foveal avascular zone (FAZ). Retinal vessel calibre was measured using a semi-automated software on fundus fluorescein images.
  
  
  RESULTS
  Of 53 patients examined, 18 (34%), 18 (34%) and 17 (32%) had no/mild, moderate and severe DMI, respectively. Persons with moderate or severe DMI had narrower mean retinal arteriolar calibre than persons with no/mild DMI (140.6 μm 95% confidence interval (CI) 134.7, 146.4 versus 150.7 μm, 95% CI 142.5, 158, p = 0.04). The association remained after multivariate adjustment for age, gender, previous panretinal photocoagulation, neovascularization at the disc and elsewhere and diabetic retinopathy severity. Increased FAZ size was also associated with narrower arteriolar calibre. Retinal venular calibre and arteriole to venule ratio (AVR) were not associated with DMI.
  
  
  CONCLUSIONS
  Retinal arteriolar narrowing was associated with moderate-to-severe macular ischaemia in eyes with diabetic retinopathy. This suggests that larger vessels other than capillaries may also be associated with DMI.
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK; Center for Vision Research, Westmead Millenium Institute, University of Sydney, Sydney, NSW, Australia.
authors.forename: Gerald
authors.initials: G
authors.lastname: Liew
authors.forename: Dawn A
authors.initials: DA
authors.lastname: Sim
authors.forename: Pearse A
authors.initials: PA
authors.lastname: Keane
authors.forename: Ava G
authors.initials: AG
authors.lastname: Tan
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Tien Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Marcus
authors.initials: M
authors.lastname: Fruttiger
authors.forename: Adnan
authors.initials: A
authors.lastname: Tufail
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Egan
mesh_terms: D000368:Aged; D001160:Arterioles / Q000473:pathology; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D007511:Ischemia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012161:Retinal Artery / Q000473:pathology*
keywords: blood flow; diabetic macular ischaemia; diabetic retinopathy; retinal imaging