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Jing Grace Wang, Mark A Latina; Comparison of Goldmann applanation tonometry and dynamic contour tonometry for measuring intraocular pressure in normal tension glaucomatous eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5319.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the intraocular pressure (IOP) measurements obtained with Goldmann Applanation Tonometry (GAT) and Pascal Dynamic Contour Tonometer (DCT) (PASCAL, Zeimer, Switzerland) in control patients and patients with normal tension glaucoma (NTG).
This is a retrospective chart review of patients who had eye exam at a glaucoma clinic at the Reading Health Center, Massachusetts. Intraocular pressures were measured with both Goldmann Applanation Tonometer and Pascal Dynamic Contour Tonometer. The difference between DCT IOP and GAT IOP (ΔIOP) and the percentage of eyes with a greater than 3 mm Hg IOP difference was determined for each group. Ocular pulse amplitude (OPA) was recorded with DCT. The data was statistically analyzed with Student’s t-test.
In control eyes (n=26, with the average age of 73.8 ± 1.7 years), the average GAT IOP was 13.43 ± 0.51 mm Hg and the average DCT IOP was 16.72 ± 2.55 mm Hg (p < 0.05). In NTG eyes (n=47, with the average age of 70.1 ± 1.6 years), the average GAT IOP was 11.55 ± 0.28 mm Hg and average DCT IOP was 16.99 ± 0.37 mm Hg (p < 0.05). The average ΔIOP was 3.30 ± 0.35 mm Hg in control eyes which is in agreement with the published results, and 5.44 ± 0.19 mm Hg in NTG eyes (p < 0.05). The percentage of eyes with a greater than 3 mm Hg ΔIOP was determined to be 47.6% of control eyes versus 95.7% of normal tension glaucoma eyes (p < 0.05). OPA was determined to be 3.19 ± 0.24 mm Hg in control eyes and 2.57 ± 0.13 mm Hg in NTG eyes (p = 0.02).
IOP measurements by DCT were significantly higher than GAT in NTG patients. The ΔIOP and the proportion of patients with a ΔIOP greater than 3 mm Hg is significantly higher in NTG eyes compared to control eyes. Our data suggest that IOP measurement by GAT may be underestimated in NTG patients. In addition, OPA values were found to be lower in patient with NTG. Our result echoes the previous reports that in NTG patients have prominent vascular dysregulation. A ΔIOP of greater than the expected 3 mm Hg in NTG patients may have clinical implications.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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