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Trabecular Meshwork Response to Pressure Elevation in the Living Human Eye
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[How does central cornea thickness influence intraocular pressure during applanation and contour tonometry?]
T Schwenteck1, M Knappe, I Moros
1thomas.schwenteck@ptb.de
Klinische Monatsblatter Fur Augenheilkunde
|September 14, 2012
Summary
Intraocular pressure (IOP) measurements using Goldmann applanation tonometry are minimally affected by central corneal thickness. This study found no need to adjust IOP readings based on corneal thickness for the tonometers examined.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Optometry
Background:
- Goldmann applanation tonometry is a standard method for measuring intraocular pressure (IOP).
- Controversy exists regarding the influence of corneal thickness on IOP measurements.
- Accurate IOP measurement is crucial, especially with devices like the Pascal contour tonometer.
Purpose of the Study:
- To analyze the correlation between intraocular pressure (IOP) and central corneal thickness.
- To evaluate the impact of corneal thickness on IOP measurements from three different tonometer types.
- To determine if IOP readings require correction based on central corneal thickness.
Main Methods:
- Compared three tonometers (AT 870, Ocuton-A, Pascal) in 158 patient eyes.
- Measured central corneal thickness using ultrasound pachymetry and Oculus Pentacam.
- Statistically evaluated the correlation using Spearman rank correlation analysis.
Main Results:
- A very weak correlation (|r| < 0.2) was found between central corneal thickness and IOP for all three tonometers.
- The IOP values were not normally distributed, while corneal thickness followed a Gaussian distribution.
- Ultrasound pachymetry showed less variance in corneal thickness measurements compared to the Pentacam.
Conclusions:
- Intraocular pressure measurements are only very weakly correlated with central corneal thickness.
- No correction of IOP values is necessary based on central corneal thickness for the studied tonometer types.
- Measuring central corneal thickness is dispensable when comparing tonometers according to ISO 8612 standards.
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