title: The effects of macular ischemia on visual acuity in diabetic retinopathy.
abstract: OBJECTIVE
  To investigate the impact of diabetic macular ischemia (DMI) on visual acuity (VA), through the analysis of novel fluorescein angiography (FA) parameters.
  
  
  METHODS
  Data were retrospectively collected over a 6-month period. DMI severity was graded using Early Treatment Diabetic Retinopathy Study (ETDRS) protocols. Custom software was used to quantify areas of the foveal avascular zone (FAZ), and of capillary nonperfusion over the papillo-macular nerve fiber layer bundle, and temporal macula, and associations tested with VA.
  
  
  RESULTS
  A total of 488 patients with type 2 diabetes mellitus and FAs of sufficient quality to allow detailed quantitative analyses were included. ETDRS-DMI SEVerity was graded as: none, 39.7%; questionable, 18.4%; mild, 25.2%; moderate, 11.0%; and severe, 5.6%. Median FAZ areas were 0.19 mm(2) (interquartile range [IQR], 0.13-0.25); 0.25 mm(2) (IQR, 0.18-0.32); 0.27 mm(2) (IQR, 0.19-0.38); 0.32 mm(2) (IQR, 0.25-0.54); and 0.78 mm(2) (IQR, 0.60-1.32), respectively, and were significantly different between all grades (P < 0.002), apart from "questionable" versus "mild" grades. Significant association of VA to FAZ area was observed only in the moderate (β = 0.406, SE = 0.101, P = 0.001) and severe (β = 0.299, SE = 0.108, P = 0.006) subgroups, but not in milder ETDRS-DMI grades. A strong association with VA was observed in cases with papillomacular ischemia (β = 1.123, SE = 0.355, P = 0.005), independent of FAZ size or the presence of macular edema.
  
  
  CONCLUSIONS
  Diabetic macular ischemia is associated with reduced VA in eyes with moderate to severe ETDRS-DMI grades of ischemia but preserved in milder grades. In addition, we describe the independent association of papillomacular nerve fiber bundle ischemia with reduced VA.
authors: Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
authors: Dawn A
authors: DA
authors: Sim
authors: Pearse A
authors: PA
authors: Keane
authors: Javier
authors: J
authors: Zarranz-Ventura
authors: Simon
authors: S
authors: Fung
authors: Michael B
authors: MB
authors: Powner
authors: Elise
authors: E
authors: Platteau
authors: Catey V
authors: CV
authors: Bunce
authors: Marcus
authors: M
authors: Fruttiger
authors: Praveen J
authors: PJ
authors: Patel
authors: Adnan
authors: A
authors: Tufail
authors: Catherine A
authors: CA
authors: Egan
mesh_terms: D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D005260:Female; D005451:Fluorescein Angiography / Q000379:methods; D006801:Humans; D007511:Ischemia / Q000503:physiopathology*; D008266:Macula Lutea / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014792:Visual Acuity / Q000502:physiology*