title: Goldmann Tonometer Prism with an Optimized Error Correcting Applanation Surface.
abstract: OBJECTIVE
  We evaluate solutions for an applanating surface modification to the Goldmann tonometer prism, which substantially negates the errors due to patient variability in biomechanics.
  
  
  METHODS
  A modified Goldmann or correcting applanation tonometry surface (CATS) prism is presented which was optimized to minimize the intraocular pressure (IOP) error due to corneal thickness, stiffness, curvature, and tear film. Mathematical modeling with finite element analysis (FEA) and manometric IOP referenced cadaver eyes were used to optimize and validate the design.
  
  
  RESULTS
  Mathematical modeling of the optimized CATS prism indicates an approximate 50% reduction in each of the corneal biomechanical and tear film errors. Manometric IOP referenced pressure in cadaveric eyes demonstrates substantial equivalence to GAT in nominal eyes with the CATS prism as predicted by modeling theory.
  
  
  CONCLUSIONS
  A CATS modified Goldmann prism is theoretically able to significantly improve the accuracy of IOP measurement without changing Goldmann measurement technique or interpretation. Clinical validation is needed but the analysis indicates a reduction in CCT error alone to less than ±2 mm Hg using the CATS prism in 100% of a standard population compared to only 54% less than ±2 mm Hg error with the present Goldmann prism.
  
  
  CONCLUSIONS
  This article presents an easily adopted novel approach and critical design parameters to improve the accuracy of a Goldmann applanating tonometer.
authors.affiliation: Intuor Technolgies, Tucson, AZ, USA ; University of Arizona Department of Ophthalmology, Tucson, AZ, USA ; University of Arizona College of Optical Science, Tucson, AZ, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: McCafferty
authors.affiliation: Intuor Technolgies, Tucson, AZ, USA.
authors.forename: Garrett
authors.initials: G
authors.lastname: Lim
authors.affiliation: Intuor Technolgies, Tucson, AZ, USA ; University of Arizona College of Optical Science, Tucson, AZ, USA.
authors.forename: William
authors.initials: W
authors.lastname: Duncan
authors.affiliation: University of Arizona College of Engineering - Department of Mechanical and Aerospace, Tucson, AZ, USA.
authors.forename: Eniko
authors.initials: E
authors.lastname: Enikov
authors.affiliation: University of Arizona Department of Ophthalmology, Tucson, AZ, USA ; University of Arizona College of Optical Science, Tucson, AZ, USA.
authors.forename: Jim
authors.initials: J
authors.lastname: Schwiegerling
keywords: corneal biomechanics; glaucoma; intraocular pressure; tonometry