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[Comparison of Goldmann tonometry, pneumotonometry and the effect of the central corneal thickness]
1Instituto Clinic de Oftalmología, Hospital Clinic i Provincial de Barcelona, Barcelona, España. nmolina@uc.cl
Purpose:
To compare the intraocular pressure (IOP) measurements using the Goldmann applanation tonometer (GAT) and contact pneumotonometer (NTC), and to evaluate the effects of central corneal thickness (CCT) on the readings.
Methods:
This was a prospective, observational clinical study, which included 96 eyes of 49 patients, 40 glaucomatous, 29 ocular hypertensive and 27 normal subjects. The IOP measurements were performed with each tonometer. The CCT was also measured.
Results:
A strong correlation coefficient between GAT and the NTC was found (Pearson=0.922, p<0.001). The mean of paired differences between GAT and NTC was 0.72 ± 2.82 mmHg. The mean difference between GAT and NTC was low at lower levels of PIO and higher at higher levels of IOP. Readings with the GAT showed a mean increase in IOP of 0.47 mmHg for every 10 μm of CCT, and the NTC 0.34 mmHg for every 10 μm, the diference was not statistically significant.
Conclusions:
The contact pneumotonometer is a reliable method in diagnosis and follow up of our population. The effect of the central corneal thickness was more important for the Goldmann applanation tonometer.