Abstract
Purpose::
Tonometry in corneal edema is a current problem. In clinical routine intraocular pressure (IOP) may be measured artificially too low in edematous thickened cornea using Goldmann applanation tonometry. The aim of this study is to compare Goldmann applanation tonometry (GAT) and dynamic contour tonometry. (DCT, Pascal, Technomed, Germany) in postsurgical corneal edema. It is claimed, that DCT measures IOP not being influenced by corneal thickness.
Methods::
Thirty-six patients with cataract were included in a prospective study. IOP was measured by means of GAT and DCT before and one day after cataract surgery. Corneal thickness was determined using a Scheimpflug camera system (Pentacam, Oculus, Germany).
Results::
After surgery corneal thickness increased significantly (pre-surgery: 545 µm, post-surgery: 685 µm, p<0.0001). No significant difference of IOP values measured with DCT compared to GAT was detected before and after cataract surgery (pre-surgery: GAT: 17 ±6 mmHg, DCT: 17 ±7 mmHg; post-surgery: GAT 16 ± 7 mmHg, DCT: 16 ±8 mmHg). IOP measured with DCT and GAT were significantly correlated (pre-surgery: r=0.83, p<0.0001; post-surgery: r=0.79, p0.0001). The difference between GAT and DCT pre-surgery compared to post-surgery was not significantly different. The IOP difference using GAT or DCT pre-surgery compared to post-surgery was not correlated to the change in corneal thickness.
Conclusions::
DCT does not give any additional information compared to GAT in patients with corneal edema. However, a marked difference in IOP values using GAT or DCT is apparent in some subjects.
Keywords: intraocular pressure • edema • clinical (human) or epidemiologic studies: systems/equipment/techniques