Comparison of dynamic contour tonometry and Goldmann applanation tonometry and their relationship to corneal properties, refractive error, and ocular pulse amplitude.

BACKGROUND

Accurate intraocular pressure (IOP) measurement is essential in diagnosing and managing glaucoma. Dynamic contour tonometry (DCT) is less dependent on corneal properties, such as thickness, elasticity, and rigidity, than Goldmann applanation tonometry (GAT). This study examined the relationship between GAT and DCT as well as their relationship with corneal properties and ocular pulse amplitude (OPA).

METHODS

GAT, DCT, OPA, pachymetry, refractive error, and corneal curvature measurements were obtained on 115 healthy volunteers.

RESULTS

Participants with thicker corneas (>or=580 microm) had higher IOP measurements with GAT than DCT (P = 0.005). Those with thinner corneas (<or=520 microm) had lower IOP with GAT versus DCT (P = 0.008). GAT and DCT readings did not differ significantly in corneas with average thickness (521 to 579 microm). A clinically significant IOP difference between DCT and GAT was found in 18.2% of subjects. A correlation was found between OPA and both refractive error and IOP (R(2) = .343, P < 0.0001). OPA was higher with increased IOP and decreased myopia.

CONCLUSION

DCT provides IOP measurements that are less dependent on corneal factors than GAT, aiding in diagnosis and treatment of patients with ocular hypertension and glaucoma. Additional studies are necessary to examine the relationship between OPA, refractive error, and IOP and its possible association with increased incidence of glaucoma in myopic patients.