title: Detection and analysis of hard exudates by polarization-sensitive optical coherence tomography in patients with diabetic maculopathy.
abstract: OBJECTIVE
  To image and analyze hard exudates (HEs) and their precursors in patients with diabetic macular edema (DME) by using polarization-sensitive optical coherence tomography (PS-OCT).
  
  
  METHODS
  Twenty-two eyes of 16 patients with DME were imaged by using color fundus photography (CF) and PS-OCT. In PS-OCT, HEs were automatically detected by their distinct polarization-scrambling qualities. Color fundus images were manually graded for the presence of HEs by two masked graders and correlated with the corresponding PS-OCT HE maps: corresponding images were overlaid and an identical grid of 128 × 128 fields was used for correlation of detected HEs.
  
  
  RESULTS
  In all eyes, HEs were present owing to DME. Agreement of a pixel-to-pixel analysis of HEs in CF images was 0.72 (Cohen's κ) between graders and 0.44 between graders and automated detection by PS-OCT. Mean ± SD detection of HEs was significantly higher in PS-OCT than in manual grading (1180.5 ± 1009.8 fields versus 828.8 ± 695.0 fields; P = 0.02). The higher detection rate of PS-OCT was confirmed by a linear regression analysis with a slope of β = 1.18 (r = 0.81).
  
  
  CONCLUSIONS
  PS-OCT enables not only two-dimensional imaging of the extent of HEs, as in CF, but also allows tissue-specific, three-dimensional imaging of HEs throughout retinal layers, based on their distinct polarization-scrambling characteristics. The higher detection rate in PS-OCT images indicates an increased sensitivity of PS-OCT imaging over conventional CF.
authors: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.
authors: Jan
authors: J
authors: Lammer
authors: Matthias
authors: M
authors: Bolz
authors: Bernhard
authors: B
authors: Baumann
authors: Michael
authors: M
authors: Pircher
authors: Bianca
authors: B
authors: Gerendas
authors: Ferdinand
authors: F
authors: Schlanitz
authors: Christoph K
authors: CK
authors: Hitzenberger
authors: Ursula
authors: U
authors: Schmidt-Erfurth
mesh_terms: D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000378:metabolism; D005122:Exudates and Transudates / Q000737:chemistry*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: color fundus photography; diabetic maculopathy; diabetic retinopathy; hard exudates; polarization-sensitive OCT