Abstract
Purpose: :
To compare the IOP measurements obtained with dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT), and to analyze the influence of central corneal thickness (CCT), age, and quality of the measurement.
Methods: :
500 healthy subjects (ages: 7 to 86 years old) were consecutively recruited. GAT (Haag Streit R900, Switzerland), DCT (SMT Swiss Micro Technology, Switzerland), and CCT (Sonomed Micropach 200P+, USA) measurements were obtained from both eyes of each individual, in this order, by three observers. The mean of 5 CCT measurements was used for analysis. DCT measurements were accepted when quality scores varied between 1(higher quality) and 3 (lower quality).
Results: :
Mean DCT measurements were 3.24 mmHg higher than GAT readings. CCT values varied between 449 and 653 µm. IOP measured by GAT correlated strongly with CCT (r2=0.28, p<0.001), whereas DCT readings correlated poorly with CCT (r2=0.01, p=0.017). Both DCT (r2<0.01, p=0.044) and GAT (r2=0.01, p<0.001) measurements poor correlated with age. Bland-Altmann analysis revealed disagreement between DCT and GAT readings, with 95% confidence intervals of + 7.06 mmHg. Quality scores for DCT measurements were 1 (n=369, 36.9%), 2 (n=340, 34.0%) and 3 (n=291, 29.1%). DCT readings with quality score of 3 (18.77 + 3.35 mmHg) were significantly higher than those with quality scores of 1 (16.61 + 2.91 mmHg) and 2 (17.44 + 2.93 mmHg) (p<0.001).
Conclusions: :
DCT is not influenced by CCT, unlike GAT. Both DCT and GAT measurements aren't influenced by age. DCT measurements with lower quality scores are associated with higher readings.
Keywords: intraocular pressure