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M.T. Nee, C. Kniestedt, R.L. Stamper; Effect of Corneal Thinning on Dynamic Contour Tonometry, Goldmann Applanation, and Pneumotonometry in a Cadaver Eye Model . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2625.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the effect of corneal thinning on intraocular pressure measurements made by Dynamic Contour Tonometry (DCT), Goldmann applanation (GAT), and pneumotonometry (PTG). Methods: Five human cadaver eyes were connected via an intracameral cannula to an open-stopcock manometric system. Intraocular pressure was then set at increments between 5 to 50 mm Hg and measurements were made using DCT, Goldmann, and pneumotonometry. An average of 65 microns of anterior corneal stroma were then ablated using the Nidek laser, and measurements were re-performed. Results: DCT was highly accurate in both pre-ablated and ablated cadaver eyes over the measured range. The average error as compared to intracameral manometry was +0.5 mm Hg and + 0.04 mm Hg for pre and post-ablated eyes, respectively. Goldmann applanation measurements before and after ablation had average errors of -4.1 mm Hg and –6.1 mm Hg, respectively; and pneumotonometry had average errors of -4.4 and –5.2 mm Hg below manometric readings. Corneal thinning accounted for an average measurement change of - 0.7 mm Hg for DCT, -1.7 mm Hg for Goldmann applanation measurements, and –0.6 mm Hg for pneumotonometry. Conclusions: DCT is quite accurate in pre-and post laser-thinned cadaver eyes. Goldmann and Pneumotonometry are less accurate than DCT and tend to underestimate IOP when compared to intracameral manometry in this cadaver eye model. Measurements made by DCT and Pneumotonometry may be more resilient to changes in corneal thickness than Goldmann applanation.
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