title: Comparison of Hanna and Hessburg-Barron trephine and punch systems using histological, anterior segment optical coherence tomography, and elliptical curve fitting models.
abstract: BACKGROUND
  This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT).
  
  
  METHODS
  Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea.
  
  
  RESULTS
  The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis), ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147) and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445). The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9-157.7) versus ±19.38° (95% CI 101.9-150.2, P = 0.492) and OCT images, ie, ±8.08° (95% CI 106.2-123.3) versus ±11.16° (95% CI 109.3-132.6, P = 0.306). The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy, ie, ±4.81° (95% CI 101.6-113.9) versus ±11.28° (95% CI 84.5-120.6, P = 0.295) and AS-OCT imaging, ie, ±9.96° (95% CI 95.7-116.4) versus ±14.02° (95% CI 91.8-123.7, P = 0.825). Statistical significance was not achieved.
  
  
  CONCLUSIONS
  The Hanna trephine and punch may be more accurate and consistent in cutting corneal buttons than the Hessburg-Barron trephine and punch when evaluated using elliptical curve fitting models, light microscopy, and AS-OCT.
authors: University of Utah, Department of Ophthalmology and Visual Sciences, Salt Lake City, UT, USA;
authors: Majid
authors: M
authors: Moshirfar
authors: Charles M
authors: CM
authors: Calvo
authors: Krista I
authors: KI
authors: Kinard
authors: Lloyd B
authors: LB
authors: Williams
authors: Shameema
authors: S
authors: Sikder
authors: Marcus C
authors: MC
authors: Neuffer