BACKGROUND: To investigate intraocular pressure (IOP) measurement values in normal tension glaucoma (NTG) eyes using two different types of tonometer that are supposed to be little affected by corneal biochemical properties. METHODS: This study included 30 normal eyes of 16 healthy subjects and 30 eyes of 16 patients with NTG. IOP was measured with a Goldmann applanation tonometer (GAT), a Pascal dynamic contour tonometer (DCT), and a Reichert ocular response analyzer (ORA) three times each for normal and NTG eyes. The main measures were GAT-IOP, DCT-IOP, corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), and central corneal thickness (CCT). RESULTS: In normal eyes, GAT-IOP was 13.2 +/- 1.4 mmHg; DCT-IOP, 13.0 +/- 1.6 mmHg; IOPcc, 13.6 +/- 2.0 mmHg; and IOPg, 12.4 +/- 2.0 mmHg. Multivariate analysis revealed no significant differences between the four measurements (p = 0.08). CCT was 524.6 +/- 27.3 microns. In NTG eyes, GAT-IOP was 13.1 +/- 1.3 mmHg; DCT-IOP, 13.7 +/- 1.3 mmHg; IOPcc, 15.2 +/- 2.0 mmHg; and IOPg, 12.7 +/- 2.0 mmHg. Multivariate analysis showed significant differences between the four measurements (p < 0.01). Sheffé's test showed that IOPcc was significantly higher than GAT-IOP, DCT-IOP, and IOPg (GAT-IOP vs IOPcc: p < 0.0001; DCT-IOP vs IOPcc: p = 0.01; IOPcc vs IOPg: p < 0.0001). CCT was 515.4 +/- 32.9 microns, with no significant difference between normal and NTG eyes (p = 0.15). CONCLUSIONS: We investigated the values of IOP in NTG eyes as measured by the DCT and ORA. IOPcc was significantly greater than GAT-IOP, DCT-IOP and IOPg in NTG eyes, suggesting the possibility that IOP values may be underestimated.
BACKGROUND: To investigate intraocular pressure (IOP) measurement values in normal tension glaucoma (NTG) eyes using two different types of tonometer that are supposed to be little affected by corneal biochemical properties. METHODS: This study included 30 normal eyes of 16 healthy subjects and 30 eyes of 16 patients with NTG. IOP was measured with a Goldmann applanation tonometer (GAT), a Pascal dynamic contour tonometer (DCT), and a Reichert ocular response analyzer (ORA) three times each for normal and NTG eyes. The main measures were GAT-IOP, DCT-IOP, corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), and central corneal thickness (CCT). RESULTS: In normal eyes, GAT-IOP was 13.2 +/- 1.4 mmHg; DCT-IOP, 13.0 +/- 1.6 mmHg; IOPcc, 13.6 +/- 2.0 mmHg; and IOPg, 12.4 +/- 2.0 mmHg. Multivariate analysis revealed no significant differences between the four measurements (p = 0.08). CCT was 524.6 +/- 27.3 microns. In NTG eyes, GAT-IOP was 13.1 +/- 1.3 mmHg; DCT-IOP, 13.7 +/- 1.3 mmHg; IOPcc, 15.2 +/- 2.0 mmHg; and IOPg, 12.7 +/- 2.0 mmHg. Multivariate analysis showed significant differences between the four measurements (p < 0.01). Sheffé's test showed that IOPcc was significantly higher than GAT-IOP, DCT-IOP, and IOPg (GAT-IOP vs IOPcc: p < 0.0001; DCT-IOP vs IOPcc: p = 0.01; IOPcc vs IOPg: p < 0.0001). CCT was 515.4 +/- 32.9 microns, with no significant difference between normal and NTG eyes (p = 0.15). CONCLUSIONS: We investigated the values of IOP in NTG eyes as measured by the DCT and ORA. IOPcc was significantly greater than GAT-IOP, DCT-IOP and IOPg in NTG eyes, suggesting the possibility that IOP values may be underestimated.
Authors: Omar S Punjabi; Hoai-Ky V Ho; Christoph Kniestedt; Alan G Bostrom; Robert L Stamper; Shan C Lin Journal: Curr Eye Res Date: 2006-10 Impact factor: 2.424
Authors: Michael Sullivan-Mee; Shavon C Billingsley; Amita D Patel; Kathy D Halverson; Brooks R Alldredge; Clifford Qualls Journal: Optom Vis Sci Date: 2008-06 Impact factor: 1.973