TJ-CEO
2010 , Vol 5 , Num 1
Comparison of Goldmann Applanation Tonometry and Tonopen XL and Effect of Central Corneal Thickness on the Measurement of Intraocular Pressure
1Haydarpaşa Numune Eğt. ve Arş. Hast., Göz Hastalıkları, İstanbul, Uzm. Dr.2Haydarpaşa Numune Eğt. ve Arş. Hast., Göz Hastalıkları, İstanbul, Asist. Dr.
3Haydarpaşa Numune Eğt. ve Arş. Hast., Göz Hastalıkları, İstanbul, Prof. Dr. Purpose: To compare Tonopen XL and Goldmann applanation tonometer in measurements of IOP and evaluate the effect of central corneal thickness (CCT) on measurements with both tonometers.
Material and Methods: Two hundred and eleven eyes of 106 patients followed in our glaucoma clinic were included in the study. IOP of each eye was measured with GAT and Tonopen three times and mean values were recorded. CCT was measured with Tomey-SP 3000 ultrasonic pachymetry. Patients were divided into three subgroups; group I: CCT≤ 520 μm, grup II: 521 μm < CCT < 569 μm, and group III: CCT≥570 μm. In each group IOP values measured with GAT and Tonopen XL were statistically compared. Correlation between CCT and IOPs measured with both tonometers was evaluated without grouping and within subgroups.
Results: Mean age of the patients was 56.18±14.23 years (13-87), mean CCT was 555±47.09 μm (403-665 μm). In all eyes IOPs measured with Tonopen was lower than IOPs measured with GAT but this difference was not statistically significant (p=0.012). In the subgroups of CCT, IOPs measured with GAT was statistically higher than IOPs measured with Tonopen only in group II (p<0.01). In all eyes there was a mild correlation between the measurements of GAT and Tonopen with CCT (r=0.385, r=0.394), and measurements of GAT and Tonopen were highly correlated with each other (r=0.834).
Conclusion: There was no statistically significant difference between IOP measurements with Tonopen and GAT. IOP values measured with Tonopen were also effected by CCT so CCT should be considered in measurements with tonopen. Keywords : Tonopen XL, Goldmann applanation tonometry, intraocular pressure, central corneal thickness