Goldmann tonometer error correcting prism: Clinical evaluation

Sean McCafferty, Garrett Lim, William Duncan, Eniko T. Enikov, Jim Schwiegerling, Jason Levine, Corin Kew

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Purpose: Clinically evaluate a modified applanating surface Goldmann tonometer prism designed to substantially negate errors due to patient variability in biomechanics. Methods: A modified Goldmann prism with a correcting applanation tonometry surface (CATS) was mathematically optimized to minimize the intraocular pressure (IOP) measurement error due to patient variability in corneal thickness, stiffness, curvature, and tear film adhesion force. A comparative clinical study of 109 eyes measured IOP with CATS and Goldmann prisms. The IOP measurement differences between the CATS and Goldmann prisms were correlated to corneal thickness, hysteresis, and curvature. Results: The CATS tonometer prism in correcting for Goldmann central corneal thickness (CCT) error demonstrated a reduction to <±2 mmHg in 97% of a standard CCT population. This compares to only 54% with CCT error <±2 mmHg using the Goldmann prism. Equal reductions of ~50% in errors due to corneal rigidity and curvature were also demonstrated. Conclusion: The results validate the CATS prism’s improved accuracy and expected reduced sensitivity to Goldmann errors without IOP bias as predicted by mathematical modeling. The CATS replacement for the Goldmann prism does not change Goldmann measurement technique or interpretation.

Original languageEnglish (US)
Pages (from-to)835-840
Number of pages6
JournalClinical Ophthalmology
StatePublished - May 3 2017


  • Appalnation tonometer
  • CATS tonometer
  • CCT
  • Central corneal thickness
  • Corneal biomechanics
  • Glaucoma
  • Goldmann
  • IOP
  • Intraocular pressure
  • Tonometer error
  • Tonometry

ASJC Scopus subject areas

  • Ophthalmology


Dive into the research topics of 'Goldmann tonometer error correcting prism: Clinical evaluation'. Together they form a unique fingerprint.

Cite this