title: In vitro pilot analysis of uniformity, circularity, and concentricity of DSAEK donor endothelial grafts prepared by a microkeratome.
abstract: OBJECTIVE
  The aim of this study was to analyze Descemet stripping automated endothelial keratoplasty donor endothelial grafts, prepared by using a microkeratome, in terms of uniformity, circularity, and concentricity.
  
  
  METHODS
  In this pilot study, 12 human donor corneas were prepared by means of a microkeratome and imaged using the Visante anterior segment optical coherence tomography along 4 meridians. The microkeratome enters and exits the corneal tissue at an angle, creating a donor graft bed with a uniform stromal (US) thickness in between the angled edges. We termed the angled portion the "nonuniform stromal transitional annulus" (STA), the point of entry and exit of the microkeratome the "epithelium-to-epithelium" (E-E) diameter, and the length of the US bed the "US" diameter. The E-E and US diameters were measured to create a model of each donor graft, from which circularity and concentricity were calculated. The STA length and height were measured, and the slope was calculated.
  
  
  RESULTS
  The mean E-E diameter was 10.69 ± 0.32 mm (range, 9.46-11.75 mm) and the mean US diameter was 8.96 ± 0.40 mm (range, 7.62-10.28 mm). The microkeratome generated elliptical rather than circular cuts, with a mean eccentricity of 0.34 ± 0.098 (range, 0.22-0.58). Eccentricity values between 0 and 1 represent ellipses, with zero characterizing a circle. The US ellipses and E-E ellipses were not concentric, with a mean deviation of the centers of the shapes of 177.06 ± 92.06 μm (range, 21.95-322.22 μm). The mean STA length was 0.73 ± 0.31 mm (range, 0.25-1.89 mm), the mean height was 0.43 ± 0.08 mm (range, 0.28-0.64 mm), and the mean slope was 34.11 ± 14.00° (range, 8.43-53.67°).
  
  
  CONCLUSIONS
  Microkeratome cuts created nonuniform, noncircular nonconcentric donor grafts. Asymmetry and nonuniformity of donor tissue may help explain suboptimal visual outcomes.
authors: *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT; †University of Arizona College of Medicine, Tucson, AZ; ‡Wilmer Eye Institute at Johns Hopkins, Baltimore, MD; §Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY; and ¶Department of Ophthalmology, State University of New York Upstate Medical University, Syracuse, NY.
authors: Majid
authors: M
authors: Moshirfar
authors: Lauren M
authors: LM
authors: Imbornoni
authors: Valliammai
authors: V
authors: Muthappan
authors: Lloyd
authors: L
authors: Williams
authors: Yousuf M
authors: YM
authors: Khalifa
authors: Allison
authors: A
authors: Jarstad
authors: Shameema
authors: S
authors: Sikder
mesh_terms: D057111:Descemet Stripping Endothelial Keratoplasty / Q000379:methods*; D004728:Endothelium, Corneal / Q000473:pathology* / Q000637:transplantation; D006801:Humans; D009929:Organ Size; D010865:Pilot Projects; D013048:Specimen Handling / Q000379:methods*; D014019:Tissue Donors; D041623:Tomography, Optical Coherence