Description

The measurement of intraocular pressure is a fundamental procedure in the diagnosis and management of primary open angle glaucoma. The purpose of this paper is to review the method of ocular tonometry and highlight recent research findings that are relevant to the  clinician. The principles of applanation tonometry are first covered and the reader reminded of how far short the globe falls of the ideal sphere required by the Imbert-Fick law. Second, the errors in measurement introduced by the corneal membrane on applanation tonometry are discussed in detail. The degree of mismatch between true intraocular pressure and that recorded through applanation tonometry are reviewed from both a theoretical perspective and experimental findings. Finally, examples of future methods of measuring intraocular pressure are illustrated. These future techniques will aim to improve on current methods of tonometry either by directly avoiding the influence of corneal structure or quantifying the level of error introduced.