title: Deformation response of paired donor corneas to an air puff: intact whole globe versus mounted corneoscleral rim.
abstract: OBJECTIVE
  To evaluate the influence of ocular shell biomechanical characteristics on corneal deformation response to an air puff.
  
  
  METHODS
  The Ohio State University, Columbus, Ohio, USA.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Twenty-four eyes of 12 human donors were obtained in matched pairs. One eye was secured in a purpose-designed whole globe mount (whole-globe group). The cornea from the fellow eye was placed in a Barron artificial anterior chamber (artificial-chamber group). The corneas were mounted sequentially and connected to a pressure-control system. Deformation data were acquired using the Corvis ST, a dynamic Scheimpflug analyzer. Internal pressure was set to 10, 20, 30, 40, and 50 mm Hg; at least 4 examinations were performed at each pressure.
  
  
  RESULTS
  Statistically significantly higher maximum deformation amplitude was observed in the whole-globe group than in the artificial-chamber group at all pressures. The mean amplitude differences were 1.006 mm ± 0.238 [SD], 0.614 ± 0.137 mm, 0.384 ± 0.099 mm, 0.229 ± 0.087 mm, and 0.133 ± 0.068 mm at 10, 20, 30, 40, and 50 mm Hg, respectively (P<.0001, P<.0001, P<.0001, P<.0001, and P<.0002, respectively). Nonlinear regression of the deformation amplitude differences between pairs showed a significant decrease with increasing pressure (P<.0001, R(2) = 0.8385).
  
  
  CONCLUSIONS
  The deformation response to an air puff was affected by the type of mount used, with a stiffer shell producing a stiffer corneal response and decreasing differences at higher internal pressures. In vivo air-puff examinations may be affected by scleral stiffness in addition to the cornea.
  
  
  BACKGROUND
  Dr. Roberts is a consultant to Oculus Optikgeräte GmbH and Ziemer Ophthalmic Systems AG and has received research funding from Carl Zeiss Meditec AG and travel funds from Sooft Italia. No other author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Department of Biomedical Engineering (Metzler, Mahmoud, Liu, Roberts) and the Department of Ophthalmology (Liu, Roberts), The Ohio State University, Columbus, Ohio, USA.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Metzler
authors.affiliation: From the Department of Biomedical Engineering (Metzler, Mahmoud, Liu, Roberts) and the Department of Ophthalmology (Liu, Roberts), The Ohio State University, Columbus, Ohio, USA.
authors.forename: Ashraf M
authors.initials: AM
authors.lastname: Mahmoud
authors.affiliation: From the Department of Biomedical Engineering (Metzler, Mahmoud, Liu, Roberts) and the Department of Ophthalmology (Liu, Roberts), The Ohio State University, Columbus, Ohio, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: From the Department of Biomedical Engineering (Metzler, Mahmoud, Liu, Roberts) and the Department of Ophthalmology (Liu, Roberts), The Ohio State University, Columbus, Ohio, USA. Electronic address: roberts.8@osu.edu.
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Roberts
mesh_terms: D000388:Air; D001696:Biomechanical Phenomena / Q000502:physiology; D003315:Cornea / Q000503:physiopathology*; D004548:Elasticity / Q000502:physiology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009799:Ocular Physiological Phenomena; D013314:Stress, Mechanical; D014019:Tissue Donors