title: New insights into the pathoanatomy of diabetic macular edema: angiographic patterns and optical coherence tomography.
abstract: OBJECTIVE
  To describe the pathoanatomy of diabetic macular edema in optical coherence tomography and its correlation with fluorescein angiography patterns.
  
  
  METHODS
  Sixty eyes of 56 patients were analyzed. Diabetic macular edema was classified into typical focal leakage (from microaneurysm), typical diffuse leakage (the capillary plexus), or combined/questionable leakage using fluorescein angiography and retinal thickness profiles. The leakage and pooling patterns in fluorescein angiography were matched to the corresponding optical coherence tomography images and analyzed.
  
  
  RESULTS
  Focal leakage shows swelling predominantly in the outer plexiform layer (OPL). Deeply located microaneurysms directly leak into the loose fiber portion of OPL (Henle layer) through the "fluid conductivity barrier" (synaptic portion of OPL). Diffuse leakage caused swelling predominantly in the inner nuclear layer and secondarily in the OPL. The deep capillary plexus is located between the two "fluid barriers" (inner plexiform layer and OPL); thus, diffuse leakage is primarily related with swelling in the inner nuclear layer. In the combined/questionable leakage, partial sections consisting of inner nuclear layer swelling and much larger areas of OPL/outer nuclear layer swelling are noticed.
  
  
  CONCLUSIONS
  Based on the concept of the fluid conductivity barrier, we revealed a correlation between the intraretinal location of the leakage source and where the fluid accumulated within the retinal layers.
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. shbyeon@yuhs.ac
authors.forename: Suk Ho
authors.initials: SH
authors.lastname: Byeon
authors.forename: Young Kwang
authors.initials: YK
authors.lastname: Chu
authors.forename: Young Taek
authors.initials: YT
authors.lastname: Hong
authors.forename: Min
authors.initials: M
authors.lastname: Kim
authors.forename: Hae Min
authors.initials: HM
authors.lastname: Kang
authors.forename: Oh Woong
authors.initials: OW
authors.lastname: Kwon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001813:Blood-Retinal Barrier / Q000502:physiology; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008269:Macular Edema / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012171:Retinal Vessels / Q000503:physiopathology; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence