Working principle

The working principle is the same as that of Baillart’s device or Mueller’s spring plunger dynamometer. An increase in intraocular pressure is induced by a force applied to the eye. In accordance with Newton’s 3rd law this force produces an equal and opposite force, which makes it possible to draw conclusions about the elevation in intraocular pressure. In theory the relation between force and elevation in intraocular pressure is not quite linear, because it depends, to some extent, on the rigidity of the globe and the time for which force is applied. In comparison with a direct measurement of pressure, however, measurement of force alone proves easier and more practicable, in that – as far as the latest development of the technique is concerned - the concept of using the contact lens itself both to increase intraocular pressure and to measure its force is both a natural progression and an entirely new idea. The contact lens is a standard three-mirror Goldmann contact lens with a measuring device on its rear side. It contains several precision sensors, which measure the force required for the increase in pressure exerted by the contact lens. The increase in intraocular pressure calculated from the size of the force is read on a LCD screen.

The dynamometric procedure presented here makes use of the outstanding optical characteristics of the Goldmann contact lens. It requires only low expenditure in terms of personnel, equipment and time.