The slit lamp of a Goldmann tonometer Semicircles seen during Goldmann tonometry through slit lamp Applanation tonometry[ edit ] In applanation tonometry the intraocular pressure IOP is inferred from the force required to flatten applanate a constant area of the cornea , for the Imbert-Fick law. Goldmann tonometry[ edit ] Goldmann tonometry is considered to be the gold standard IOP test and is the most widely accepted method. The examiner then uses a cobalt blue filter to view two green semi circles. The force applied to the tonometer head is then adjusted using a dial connected to a variable tension spring until the inner edges of the green semicircles in the viewfinder meet. When an area of 3.
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Checking for direct PDF access through Ovid Abstract Purpose:With tonometers currently in use intraocular pressure is indirectly determined by measuring a physical quantity related to a specified deformation of the cornea. We present a new principle of direct, continuous, and transcorneal intraocular pressure measurement, describe its theoretical foundation, and evaluate its application on the basis of an in vitro model.
Methods:On a living human eye an optimized pressure-sensitive contact surface was determined by performing pressure measurements with differently shaped tonometer heads. Based on these results and on the theoretical model, a Dynamic Contour Tonometer was constructed and validated on eye bank bulbi against a manometric reference pressure. Results:A concave contact surface with a radius of curvature of A sensor integrated into the surface having the same contour measures the intraocular pressure closely to the manometric reference pressure in human cadaver eyes.
The accuracy of the tonometer appears to be unaffected by variations in corneal properties. Conclusion:Dynamic Contour Tonometry eliminates most of the systematic errors arising from individual changes of corneal properties that adversely influence all types of applanation tonometers. The advantage of measuring the true pressure in combination with the capability of registering dynamic pressure fluctuations discloses new tonometric opportunities to diagnose and classify different types of glaucoma.
Dynamic contour tonometry: principle and use.