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Correlation between Goldmann applanation tonometry and rebound tonometry in relation to central corneal thickness
Author(s) -
BRANDTNER H,
HITZL W,
STROHMAIER C,
ABRI S,
WINTERSTELLER CH,
HOHENSINN M,
RUCKHOFER J,
STOIBER J,
GRABNER G,
REITSAMER HA
Publication year - 2009
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2009.227.x
Subject(s) - ophthalmology , medicine , applanation tonometry , linear correlation , positive correlation , significant difference , optometry , correlation , goldmann applanation tonometer , intraocular pressure , mathematics , statistics , blood pressure , arterial stiffness , geometry
Purpose To investigate the influence of central corneal thickness (CCT) on the ICare Rebound Tonometer (RBT) measurements and to verify the correlation of RBT and Goldmann applanation tonometry (GAT). Methods The current study contains data from 230 eyes from a mixed population of the outpatient departments of the University Eye Clinic Salzburg. The mean‐age was 67.19 years (SD +/‐ 11.87). The study was explained to the patients and their informed consent was obtained. The IOP was measured with both the GAT and the ICare‐tonometer; in addition the CCT was determined with standard pachymetry. Results We were able to show a good linear correlation between GAT and RBT readings (r=0.9). Over the whole range of IOP we could observe a good correlation of both tonometers with the tendency of a slight overestimation of the IOP in RBT readings. CCT has a stronger impact on the results of RBT than on the results of GAT. In thin corneas RBT tends to underestimate the GAT readings, whereas in thick corneas RBT overestimates the GAT readings. Although the correlation factor between GAT and RBT is high, significant differences can be seen in the Bland‐Altman analysis. Only in 15% of all measurements no differences in results between the two methods were observed. In 26% the difference was 1 mmHg, in 23% 2 mmHg, in 19% 3 mmHg and in 16% 4 or more mmHg. The analysis also revealed a correlation of r=‐0.4 between CCT and the difference in results of the two methods. Conclusion In cases where an exact measurement of the IOP is important RBT would not be the first choice. Also formulas to correct for the dependency of RBT on CCT would improve the results only marginally.