title: Lesion size detection in geographic atrophy by polarization-sensitive optical coherence tomography and correlation to conventional imaging techniques.
abstract: OBJECTIVE
  To investigate the reproducibility of automated lesion size detection in patients with geographic atrophy (GA) using polarization-sensitive spectral-domain optical coherence tomography (PS-OCT) and to compare findings with scanning laser ophthalmoscopy (SLO), fundus autofluorescence (FAF), and intensity-based spectral-domain OCT (SD-OCT).
  
  
  METHODS
  Twenty-nine eyes of 22 patients with GA were examined by PS-OCT, selectively identifying the retinal pigment epithelium (RPE). A novel segmentation algorithm was applied, automatically detecting and quantifying areas of RPE atrophy. The reproducibility of the algorithm was assessed, and lesion sizes were correlated with manually delineated SLO, FAF, and intensity-based SD-OCT images to validate the clinical applicability of PS-OCT in GA evaluation.
  
  
  RESULTS
  Mean GA lesion size of all patients was 5.28 mm(2) (SD: 4.92) in PS-OCT. Mean variability of individual repeatability measurements was 0.83 mm(2) (minimum: 0.05; maximum: 3.65). Mean coefficient of variation was 0.07 (min: 0.01; max: 0.19). Mean GA area in SLO (Spectralis OCT) was 5.15 mm(2) (SD: 4.72) and 2.5% smaller than in PS-OCT (P = 0.9, Pearson correlation coefficient = 0.98, P < 0.01). Mean GA area in intensity-based SD-OCT pseudo-SLO images (Cirrus OCT) was 5.14 mm(2) (SD: 4.67) and 2.7% smaller than in PS-OCT (P = 0.9, Pearson correlation coefficient = 0.98, P < 0.01). Mean GA area of all eyes measured 5.41 mm(2) (SD: 4.75) in FAF, deviating by 2.4% from PS-OCT results (P = 0.89, Pearson correlation coefficient = 0.99, P < 0.01).
  
  
  CONCLUSIONS
  PS-OCT demonstrated high reproducibility of GA lesion size determination. Results correlated well with SLO, FAF, and intensity-based SD-OCT fundus imaging. PS-OCT may therefore be a valuable and specific imaging modality for automated GA lesion size determination in scientific studies and clinical practice.
authors.affiliation: Department of Ophthalmology, Medical University of Vienna, Austria.
authors.forename: Christopher
authors.initials: C
authors.lastname: Schütze
authors.forename: Matthias
authors.initials: M
authors.lastname: Bolz
authors.forename: Ramzi
authors.initials: R
authors.lastname: Sayegh
authors.forename: Bernhard
authors.initials: B
authors.lastname: Baumann
authors.forename: Michael
authors.initials: M
authors.lastname: Pircher
authors.forename: Erich
authors.initials: E
authors.lastname: Götzinger
authors.forename: Christoph K
authors.initials: CK
authors.lastname: Hitzenberger
authors.forename: Ursula
authors.initials: U
authors.lastname: Schmidt-Erfurth
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D005451:Fluorescein Angiography; D057092:Geographic Atrophy / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D015203:Reproducibility of Results; D055213:Retinal Pigment Epithelium / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000295:instrumentation*; D014792:Visual Acuity / Q000502:physiology