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Related Experiment Video

Updated: Mar 26, 2026

Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter
05:14

Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter

Published on: September 16, 2025

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Corneal astigmatism in applanation tonometry.

H H Mark1, T L Mark

  • 1iimd@aol.com

Eye (London, England)
|July 12, 2003
PubMed
Summary

Goldmann tonometer readings correlate with corneal curvature. Flatter corneas yield lower readings, indicating scale values may not reflect true intraocular pressure.

Area of Science:

  • Ophthalmology
  • Biomedical Engineering

Background:

  • Intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
  • The Goldmann applanation tonometer (GAT) is a widely used device for IOP assessment.
  • Corneal properties are known to influence IOP measurements.

Purpose of the Study:

  • To quantitatively correlate Goldmann tonometer scale readings with corneal curvature.
  • To investigate the impact of corneal topography on tonometric measurements.

Main Methods:

  • Corneal curvature was measured in horizontal and vertical meridians in 30 eyes.
  • Applanation tonometry using the Goldmann tonometer was performed on the same eyes.
  • Statistical analysis was conducted using Microsoft Excel and SAS System.

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Main Results:

  • A strong positive correlation was observed between tonometric readings and corneal curvature.
  • Flatter corneal curvatures resulted in lower Goldmann tonometer scale readings.
  • Conversely, steeper corneal curvatures were associated with higher scale readings.

Conclusions:

  • Goldmann tonometer scale readings are influenced by corneal curvature and astigmatism.
  • The device's scale may not directly represent true intraocular pressure in mmHg.
  • Considering corneal variables is essential for accurate tonometric interpretation in clinical practice.