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B.E. Frueh, M. Iliev, K. Katsoulis; Dynamic Contour Tonometry for Recording IOP in Pathological Corneas . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2765.
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Purpose: To assess dynamic contour tonometry (DCT), a novel method for measuring IOP, in pathological corneas. Previous studies have indicated that DCT is not influenced by corneal thickness or curvature. Methods: 54 eyes of 29 patients were studied. 33 eyes were normal, 7 corneas had keratoconus or irregular astigmatism after penetrating keratoplasty, and 14 eyes had glaucoma but normal corneas. IOP was measured with DCT and Goldman applanation tonometry (GAT). Central corneal thickness (CCT) was recorded with optical low coherence reflectometry. Correlation coefficient and paired t–test were calculated. Results: Mean (±SD) DCT was 18.1±4.3 mm Hg , GAT 15.9±4.7 mm Hg. Mean pachymetry was 561±35.7 µm (range, 488–630µm). Paired t–test showed a statistical significant difference between the 2 tonometry methods (p6.0 mm Hg (considered to be clinically significant). Of these eyes, only 4 were normal (12%), while 5 (including keratoconus) had irregular astigmatism (71.5%), and 4 glaucoma (28.6%) –with pachymetry values between 505 and 570 um–. In this subgroup of 13 eyes, mean DCT was 19.35±5.7 mm Hg and GAT 14.42±5.8 mm Hg. Conclusions: In normal eyes, there was a good agreement between DCT and GAT, and both methods correlated well with pachymetry. For pathological corneas, the difference in IOP readings is greater, with GAT underestimating pressure in eyes with irregular astigmatism after keratoplasty and in keratoconus.
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