title: Topographic thickness of Bowman's layer determined by ultra-high resolution spectral domain-optical coherence tomography.
abstract: OBJECTIVE
  To characterize the thickness profile of the corneal epithelium and the Bowman's layer across the horizontal meridian.
  
  
  METHODS
  Forty-four eyes of 22 healthy subjects were investigated in this study. Ultra-high resolution anterior segment spectral domain-optical coherence tomography (SD-OCT) was used to assess the topographic thickness of the epithelium and the Bowman's layer across the cornea. Thicknesses at five locations, including the center, midperiphery, and periphery close to the limbus, on both the nasal and the temporal sides along the horizontal meridian, were analyzed.
  
  
  RESULTS
  Mean epithelial thickness at the central cornea was 52.5 ± 2.4 μm. It increased gradually from the center to the periphery (P < 0.001). There was no significant difference between the nasal side and the temporal side for epithelial thickness. The central Bowman's layer thickness was 17.7 ± 1.6 μm, and it remained constant from the center to the midperiphery (P > 0.05). However, thicknesses at the nasal and temporal periphery, 20.0 ± 1.9 μm and 19.8 ± 2.2 μm, respectively, were significantly greater than the central and midperipheral thicknesses (P < 0.001). Nasal and temporal thicknesses were similar on either side of the center.
  
  
  CONCLUSIONS
  The epithelium and the Bowman's layer were not evenly distributed across the horizontal meridian of the cornea. SD-OCT provided useful information about topographic thickness of the different corneal layers in vivo.
authors: School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, Zhejiang, China.
authors: Aizhu
authors: A
authors: Tao
authors: Jianhua
authors: J
authors: Wang
authors: Qi
authors: Q
authors: Chen
authors: Meixiao
authors: M
authors: Shen
authors: Fan
authors: F
authors: Lu
authors: Sander R
authors: SR
authors: Dubovy
authors: Mohamed Abou
authors: MA
authors: Shousha
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D019412:Anatomy, Cross-Sectional; D000886:Anthropometry; D050541:Bowman Membrane / Q000033:anatomy & histology*; D019781:Corneal Topography; D019573:Epithelium, Corneal / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult