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Goldmann applanation tonometer is based on the Imbert–Fick principle, which states that for a dry thin-walled sphere, the pressure (P) inside the sphere equals the force (F) necessary to flatten its surface divided by the area (A) of flattening (i.e. P = F/A).
Armand Imbert (1850-1922) and Adolf Fick (1829-1901) both demonstrated, independently of each other, that in ocular tonometry the tension of the wall can be neutralized when the application of the tonometer produces a flat surface instead of a convex one, and the reading of the tonometer (P) then equals (T) the IOP," whence all forces cancel each other.
The Schiotz tonometer consists of a curved footplate which is placed on the cornea of a supine patient. A weighted plunger attached to the footplate sinks into the cornea. A scale then gives a reading depending on how much the plunger sinks into the cornea, and a conversion table converts the scale reading into IOP measured in mmHg.
Goldmann applanation tonometry (GAT) is considered to be the gold standard IOP test and is the most widely accepted method. [4] [5] A special disinfected prism is mounted on the tonometer head and then placed against the cornea. The examiner then uses a cobalt blue filter to view two green semicircles.
A patient in front of a tonometer. Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. [1] Most tonometers are calibrated to measure pressure in millimeters of mercury .
The formal definition of calibration by the International Bureau of Weights and Measures (BIPM) is the following: "Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or ...
A blood pressure (BP) measurement system specifically a writ-bound BP monitor works through an applanation tonometry with a hemispheric plunger set on the radial artery. Devices such as an ambulatory blood pressure improved the management of hypertension, but remain not being widely used and inconvenient.
Goldmann's tonometer, [4] Goldmann's indirect goniolens, Goldmann-Weekers Dark Adaptometer™, [5] and; fluorophotometer. He was the author of more than 200 articles in peer-reviewed journals. At the eye clinic of the University of Bern there is a Hans-Goldmann-Stiftung (Foundation) for orthoptics. His name is attached to Goldmann-Favre ...