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[Applanation tonometry in "normal" patients and patients after LASIK]
M Kohlhaas1, E Spörl, A G Böhm
1Universitäts-Augenklinik Carl Gustav Carus, Dresden. markus.kohlhaas@uniklinikum-dresden.de
Klinische Monatsblatter Fur Augenheilkunde
|October 22, 2005
Summary
Corneal thickness and curvature significantly impact intraocular pressure (IOP) measurements. Adjustments are needed for accurate IOP readings, especially after LASIK surgery.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Optometry
Background:
- Morphological eye parameters were previously thought not to influence tonometry.
- This study investigates the impact of corneal thickness, curvature, and axial length on applanation tonometry.
- Understanding these influences is crucial for accurate intraocular pressure assessment.
Purpose of the Study:
- To determine if corneal thickness, curvature, and axial length affect tonometry results.
- To evaluate the accuracy of intraocular pressure (IOP) measurements in relation to corneal biomechanics.
- To develop correction methods for IOP readings influenced by corneal parameters.
Main Methods:
- Prospective study of 125 normal eyes and 102 eyes post-LASIK.
- Intraocular pressure was manometrically set and measured using a Perkins tonometer.
- Corneal thickness, curvature, and axial length were measured before and after LASIK.
Main Results:
- Significant correlation found between measured IOP and corneal thickness (r² = 0.78–0.83).
- Post-LASIK, IOP decreased, showing significant correlation with corneal thickness and curvature (r² = 0.631).
- Corneal biomechanical changes after LASIK necessitate IOP correction.
Conclusions:
- Corneal thickness significantly affects Goldmann applanation tonometry.
- The "Dresden Correction Table" is recommended for accurate IOP measurement.
- Post-LASIK IOP measurements require correction due to altered corneal biomechanics, thickness, and curvature.