title: In vivo identification of alteration of inner neurosensory layers in branch retinal artery occlusion.
abstract: OBJECTIVE
  To characterise the extension and progression of alteration of neurosensory layers following acute and chronic branch retinal artery occlusion (BRAO) in vivo using spectral-domain optical coherence tomography.
  
  
  METHODS
  In this observational case series, eight eyes with acute BRAO and nine eyes with chronic BRAO were analysed using a Spectralis Heidelberg Retina Angiograph (HRA)+optical coherence tomography system including eye tracking. Patients with acute BRAO were examined within 36±5 h after primary event and at weekly/monthly intervals thereafter. Segmentation measurements of all individual neurosensory layers were performed on single A-scans at six locations in affected and corresponding non-affected areas. The thickness values of the retinal nerve fibre layer together with the ganglion cell layer (NFL/GCL), inner plexiform layer (IPL), inner nuclear layer together with outer plexiform layer (INL/OPL), outer nuclear layer (ONL), and photoreceptor layers together with the retinal pigment epithelium (PR/RPE) were measured and analysed.
  
  
  RESULTS
  Segmentation evaluation revealed a distinct increase in thickness of inner neurosensory layers including the NFL/GCL (35%), IPL (80%), INL/OPL (48%) and mildly the ONL by 21% in acute ischaemia compared with corresponding layers in non-ischaemic areas. Regression of intraretinal oedema was followed by persistent retinal atrophy with loss of differentiation between IPL and INL/OPL at month 2. In contrast, the ONL and subjacent PR/RPE retained their physiological thickness in patients with chronic BRAO.
  
  
  CONCLUSIONS
  In vivo assessment of retinal layer morphology allows a precise identification of the pathophysiology in retinal ischaemia.
authors.affiliation: Department of Ophthalmology, Medical University of Vienna, Austria, Waehringer Guertel 18-20, Vienna A-1090, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Ritter
authors.forename: Stefan
authors.initials: S
authors.lastname: Sacu
authors.forename: Gábor G
authors.initials: GG
authors.lastname: Deák
authors.forename: Karl
authors.initials: K
authors.lastname: Kircher
authors.forename: Ramzi G
authors.initials: RG
authors.lastname: Sayegh
authors.forename: Christian
authors.initials: C
authors.lastname: Pruente
authors.forename: Ursula M
authors.initials: UM
authors.lastname: Schmidt-Erfurth
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015356:Retinal Artery Occlusion / Q000175:diagnosis* / Q000503:physiopathology; D055351:Retinal Neurons / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology