title: Histopathological correlation of corneal diseases with optical coherence tomography.
abstract: OBJECTIVE
  To correlate the cross-sectional images of corneal diseases obtained by optical coherence tomography (OCT) with light microscopy (LM) to determine the corneal components represented in OCT images.
  
  
  METHODS
  In a prospective comparative tissue study clinicopathological correlations of six patients with pseudophakic bullous keratopathy ( n=3), advanced keratoconus ( n=1), persistent epithelial defect with corneal thinning ( n=1), and retrocorneal membrane ( n=1) were included. Immediately before a planned penetrating keratoplasty (PKP) noncontact slitlamp-adapted OCT of the cornea was performed. After PKP and following standard histological processing the specimens were examined under LM to compare qualitatively the morphology, and quantitatively the morphometry at selected corneal locations.
  
  
  RESULTS
  The cross-sectional optical-reflectivity profiles enabled the reproducible morphological evaluation of the corneal structures and changes. Layers of relative high reflectivity corresponded to the anterior corneal surface and internal stromal layers. In contrast, the deeper corneal epithelial layer demonstrated relative low reflectivity by OCT. An increase in light reflectivity corresponded to corneal scarring, irregularities of the corneal lamellae, and deposition of basal membrane material. Low signal intensity was particularly due to fluid accumulations and shadowing. The most prominent changes were caused by corneal scars or edematous tissue. The morphometric analysis with OCT revealed, in this study, thickness measurements ranging from 31 to 902 micro m. Although the mean OCT thickness values were up to 9% ( P=0.014) higher than those derived from LM, there was a significant positive correlation (r=0.94; P<0.001) between corneal OCT and the light-microscopic measurements.
  
  
  CONCLUSIONS
  Noncontact slitlamp-adapted corneal OCT revealed a good correlation with histological sections. The differences noted were partly related to shrinking processes during preparation. Thus, with certain limitations, OCT allows a non-invasive optical biopsy of pathological structures in corneal diseases.
authors.affiliation: Klinik für Augenheilkunde, Vivantes Klinikum Neukölln, Rudower Strasse 48, 12351 Berlin, Germany. augen@knk-berlin.de
authors.forename: Christopher
authors.initials: C
authors.lastname: Wirbelauer
authors.forename: Jörg
authors.initials: J
authors.lastname: Winkler
authors.forename: Gerd O
authors.initials: GO
authors.lastname: Bastian
authors.forename: Heike
authors.initials: H
authors.lastname: Häberle
authors.forename: Duy Thoai
authors.initials: DT
authors.lastname: Pham
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000473:pathology; D003316:Corneal Diseases / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007368:Interferometry; D015948:Keratoplasty, Penetrating / Q000473:pathology*; D008027:Light; D008875:Middle Aged; D011446:Prospective Studies; D014054:Tomography / Q000379:methods