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Background: Although it is widely accepted that the Pascal dynamic contour tonometry (DCT) reading is higher than Goldmann applanation tonometry (GAT) in normal range of intraocular pressure (IOP), it remains unclear whether DCT reading is higher or lower than GAT in an eye with severely elevated IOP. This study aimed to compare the IOP measurements obtained using GAT with DCT in eyes with elevated IOP and to compare the GAT and DCT measurements in the same eyes after subsequent normalization of the IOP with medical therapy. Methods: Eyes with IOP greater than 30 mmHg as measured by GAT at the initial examination were enrolled for a prospective study. IOP was measured by GAT and DCT. Central corneal thickness (CCT) was measured using a specular microscope. When the GAT-IOP was reduced to below 21 mmHg with medical therapy, DCT and CCT measurements were taken in the same eyes. Results: Measurements from 27 patients were suitable for statistical analysis. At baseline examination, the mean DCT was significantly lower than their mean GAT (30.0(plus or minus)5.8 mmHg vs 38.7(plus or minus)9.1 mmHg, P<0.001). After the IOP-lowering medical therapy had been instituted, the mean DCT was significantly higher than the mean GAT (17.9(plus or minus)3.1 mmHg vs 15.6(plus or minus)2.7 mmHg, P<0.001). The mean post-treatment IOP reduction was 12.1 mmHg (40.3%) by DCT and 23.1 mmHg (59.7%) by GAT. The mean CCT showed no significant difference after the IOP-lowering therapy (537.7(plus or minus)31.4 (mu)m vs 543.1(plus or minus)47.7 (mu)m, P=0.596). The mean ocular pulse amplitude decreased significantly after the medical treatment (3.16(plus or minus)1.24 mmHg vs 2.07(plus or minus)0.93 mmHg, P<0.001). Conclusion: DCT-IOP, which is higher than GAT-IOP in normotensive eyes, is lower in eyes with GAT-IOP exceeding 30 mmHg. (copyright) 2010 Springer-Verlag.
Y. Y. Kim. Department of Ophthalmology, Korea University, Guro Hospital, 97 Guro-dong-gil, Guro-gu, Seoul 152-703, South Korea. yongykim@korea.ac.kr
6.1.1 Devices, techniques (Part of: 6 Clinical examination methods > 6.1 Intraocular pressure measurement; factors affecting IOP)