title: High-resolution imaging of the human retina in vivo after scatter photocoagulation treatment using a semiautomated laser system.
abstract: OBJECTIVE
  To image the ultrastructural morphology of retinal laser effects and their healing response in vivo using spectral domain optical coherence tomography (SD-OCT).
  
  
  METHODS
  Prospective, interventional study.
  
  
  METHODS
  Ten patients undergoing panretinal photocoagulation for proliferative diabetic retinopathy.
  
  
  METHODS
  Panretinal photocoagulation (PRP) was performed using a semiautomated patterned scanning laser system providing a raster of effects with homogenous intensity. Retinal morphology and localization of effects owing to laser-tissue interaction were imaged at 1 day, 1 week, and at monthly intervals for 6 months. The characteristic, specific structural changes during the healing process were followed over time using an SD-OCT device (Spectralis OCT) allowing for high-resolution raster scanning of the entire lesion pattern with identification of identical retinal sites (tracking modality).
  
  
  METHODS
  Retinal morphology and localization of effects of photocoagulation on SD-OCT images.
  
  
  RESULTS
  At day 1 after PRP, the photocoagulation effects were sharply delineated from the surrounding unaffected retina and all spots seemed to be identical in size and location. The area of tissue destruction was confined to the outer retinal layers, extending from the outer nuclear layer (ONL) to the retinal pigment epithelium (RPE). At 1 week, images showed a progressive loss of the affected outer retinal layers, namely, the ONL and the outer plexiform layer. Concomitant distortion of the inner nuclear and plexiform layers generated a pattern of "archways" between adjacent laser spots. The photoreceptor layers (PRL) seemed to be eliminated in the photocoagulated area, particularly at the borders of each lesion. The lesion center contained a condensed RPE and PRL segment. The ONL recovered partially, but the PRL inner and outer segments remained absent. During the long-term follow-up, RPE cells migrated to the center of the lesion, forming a hyperplastic scar.
  
  
  CONCLUSIONS
  The characteristic morphology of retinal photocoagulation effects in vivo and over time was identified for the first time in human eyes using SD-OCT. The OCT imaging demonstrated a well-defined reproducible area of destruction confined to the outer retinal layers. Healing proceeded as the condensation of the RPE and PRL in the lesion center.
authors.affiliation: Department of Ophthalmology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kriechbaum
authors.forename: Matthias
authors.initials: M
authors.lastname: Bolz
authors.forename: Gabor G
authors.initials: GG
authors.lastname: Deak
authors.forename: Sonja
authors.initials: S
authors.lastname: Prager
authors.forename: Christoph
authors.initials: C
authors.lastname: Scholda
authors.forename: Ursula
authors.initials: U
authors.lastname: Schmidt-Erfurth
mesh_terms: D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D017075:Laser Coagulation; D008297:Male; D011446:Prospective Studies; D012160:Retina / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology; D014945:Wound Healing