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The effect of corneal thickness on applanation tonometry
M M Whitacre1, R A Stein, K Hassanein
1Department of Ophthalmology, University of Missouri, Kansas City School of Medicine 64108.
American Journal of Ophthalmology
|May 15, 1993
Summary
Corneal thickness significantly impacts intraocular pressure measurements. Thin corneas underestimate pressure, while thick corneas overestimate it, necessitating thickness measurement for accurate readings.
Area of Science:
- Ophthalmology
- Biomedical Engineering
Background:
- Intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
- Tonometry methods, like Perkins tonometry, are widely used but can be affected by corneal properties.
- Goldmann applanation tonometry is a standard but its accuracy is known to be influenced by corneal thickness.
Purpose of the Study:
- To investigate the relationship between corneal thickness and the accuracy of Perkins tonometry.
- To determine the extent of IOP measurement errors associated with varying corneal thicknesses.
Main Methods:
- Simultaneous manometry and Perkins tonometry were conducted.
- Measurements were taken on 15 eyes post-intraocular procedures.
- Data were analyzed to find correlations between corneal thickness and tonometry error.
Main Results:
- A statistically significant relationship was found between corneal thickness and Perkins tonometry error.
- Thin corneas led to IOP underestimations (up to 4.9 mm Hg).
- Thick corneas resulted in IOP overestimations (up to 6.8 mm Hg).
Conclusions:
- Corneal thickness is a critical factor influencing Perkins tonometry accuracy.
- Accurate interpretation of IOP readings requires considering corneal thickness, especially in eyes with thin corneas.
- Measuring corneal thickness is essential for reliable Goldmann applanation tonometry results.