title: Deep Capillary Macular Perfusion Indices Obtained with OCT Angiography Correlate with Degree of Nonproliferative Diabetic Retinopathy.
abstract: OBJECTIVE
  To evaluate the integrity of macular and temporomacular vasculature in nonproliferative diabetic retinopathy (NPDR) with noninvasive optical coherence tomography angiography (OCTA) and correlate perfusion indices with degree of NPDR.
  
  
  METHODS
  In this prospective observational cross-sectional study, 102 eyes with newly diagnosed NPDR (mild NPDR, 36; moderate NPDR, 21; severe NPDR, 13; NPDR with diabetic macular edema [DME], 32) underwent OCTA. Sixty eyes of normal subjects served as control. Degree of NPDR (based on Early Treatment Diabetic Retinopathy Study criteria) was confirmed with fluorescein angiography. Automated OCTA/split-spectrum amplitude decorrelation angiography software generated perfusion indices (vessel density and flow index) from images of the retina. The perfusion index of superficial and deep retinal plexuses was obtained in both perifoveal (central 1-3 mm) and parafoveal (3-6 mm) areas.
  
  
  RESULTS
  Deep plexus parafoveal vessel density was 25.23% (±6.1) in mild NPDR, 20.16% (±6.16) in moderate NPDR, 11.16% (±4.16) in severe NPDR, and 17.91% (±4.42) in NPDR + DME compared to normal subjects (36.93% [±8.1]; (p<0.01). Spearman correlation coefficient (rs) between vessel density and level of NPDR severity in the parafoveal region showed inverse correlation for both superficial (rs-0.87; p = 0.083) and deep (rs-0.96; p = 0.017) plexus. Similarly, when vessel density of the perifoveal region was compared with level of NPDR severity, inverse correlation was noted in both superficial (rs-0.85; p = 0.08) and deep (rs-0.98; p = 0.011) plexus.
  
  
  CONCLUSIONS
  Optical coherence tomography angiography clearly delineated the retinal microcirculation and allowed quantification of vascular perfusion of each layer. As diabetic retinopathy progressed, a decrease in perfusion index is more pronounced in the deep retinal plexus and precedes changes in superficial plexus.
authors.affiliation: Department of Ophthalmology, University of Florida College of Medicine, Jacksonville, Florida - USA.
authors.forename: Kumar
authors.initials: K
authors.lastname: Sambhav
authors.affiliation: Department of Ophthalmology, University of Florida College of Medicine, Jacksonville, Florida - USA.
authors.forename: Khaled K
authors.initials: KK
authors.lastname: Abu-Amero
authors.affiliation: Department of Ophthalmology, University of Florida College of Medicine, Jacksonville, Florida - USA.
authors.forename: Kakarla V
authors.initials: KV
authors.lastname: Chalam
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002196:Capillaries / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D005451:Fluorescein Angiography / Q000379:methods*; D006801:Humans; D008269:Macular Edema / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012160:Retina / Q000503:physiopathology; D012171:Retinal Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012984:Software; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult
keywords: Diabetic retinopathy; Nonproliferative diabetic retinopathy; Optical coherence tomography angiography; Perfusion indices; Split-spectrum amplitude decorrelation angiography