Pachymetry is the study of corneal thickness or, more precisely, the measurement of corneal thickness at the center of the cornea, performed non-contact with a scheimpflug or OCT camera or touch with an ultrasound probe. No pupil dilation is required for the test. Evaluation of corneal thickness is a mandatory test in patients with glaucoma and ocular hypertension, and is also performed before surgical procedures, including laser procedures, on the cornea, as well as in the diagnosis of corneal cone and other corneal disorders.

The test has a crucial impact on the assessment of intraocular pressure values, as it makes it possible to determine whether the measured intraocular pressure is overestimated or underestimated by overlooking the existence of a thicker or thinner cornea.

It has been proven that Patients with corneas thicker than standard corneas may have higher pressures, which, however, are not necessarily anything to worry about. Patients with thin corneas, on the other hand, often have underestimated intraocular pressure – the pressure values are artificially low.

Tactile pachymetry is performed using ultrasonic pachymeters. The test requires contact between the camera tip and the patient’s cornea. It is painless because the cornea is anesthetized beforehand with drops. Several measurements of central corneal thickness are taken during the examination. The results are averaged, which makes it possible to read and apply the appropriate correction to the value of intraocular pressure. Non-contact pachymetry is performed as part of corneal tomography using an ultrasound camera. In this case, there is no contact between the camera and the cornea, which reduces the risk of infection and unpleasant sensations. This method has the advantage of profiling the thickness of the entire cornea, which allows for a more precise diagnosis of various corneal conditions – in contrast to tactile pachymetry, which measures the thickness of the cornea in only one selected area. NOTE: test results from both methods cannot be used interchangeably. There may be differences between them due to the application of corrections calculated for a particular measurement method.

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