Comparison of Dynamic Contour Tonometry and Goldmann Applanation Tonometry in African American Subjects
Received 15 March 2006; accepted 28 June 2006. published online 01 December 2006.
Purpose
To evaluate the relationship between intraocular pressure (IOP) measurements obtained by dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in African Americans and to assess whether these measures were influenced by ocular parameters including corneal thickness, corneal curvature, and axial length.
Design
Observational clinical study.
Participants
The study included 176 eyes of 94 African Americans.
Methods
All participants underwent IOP evaluation with DCT and GAT, as well as measurements of central corneal thickness (CCT), corneal curvature, corneal astigmatism, spherical equivalent, and axial length.
Main Outcome Measures
Univariate and multiple regression analyses were used to evaluate the associations between IOP (as measured with DCT and GAT) and CCT, corneal curvature, corneal astigmatism, spherical equivalent, axial length, and age. Bland-Altman plots were used to evaluate the agreement between IOP measurements obtained by DCT and GAT.
Results
In multiple regression analysis, GAT IOP measurements were significantly associated with CCT (P<0.001) and age (P = 0.003), whereas DCT IOP measurements were associated only with age (P = 0.027). The difference between DCT and GAT IOP measurements was significantly influenced by corneal thickness (P<0.001) and ocular pulse amplitude (OPA; P = 0.004). Patients with thick corneas tended to have higher GAT IOP measurements compared with DCT, whereas in patients with thin corneas, GAT IOP measurements tended to be lower than DCT measurements. Larger values of OPA were associated with a decrease in the difference between DCT and GAT measurements, whereas smaller values of OPA were associated with an increase in the difference between DCT and GAT measurements.
Conclusions
Dynamic contour tonometry measurements in African Americans seem to provide an estimate of IOP that is less influenced by corneal properties than those provided by GAT.
Hamilton Glaucoma Center and Department of Ophthalmology, University of California, San Diego, La Jolla, California.
Correspondence to Felipe A. Medeiros, MD, Hamilton Glaucoma Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0946.
Manuscript no. 2006-332.
Swiss Microtechnology AG, Zurich, Switzerland, donated to Dr Weinreb a Pascal dynamic contour tonometer for research.
The authors have no financial interest in any of the products mentioned in the article.
ABSTRACT