[Comparison of the corneal thickness as measured by Visante anterior segment OCT versus ultrasound technique]

Pachymetry is important in relation to the intraocular pressure (IOP) and can either be contact measured or non-contact measured. Depending on the corneal thickness it is possible to get false IOP measurements up to +/-5 mmHg. Thus, it is necessary to know the exact corneal thickness. A new non-contact technique for measuring the corneal thickness is available with the Visante anterior segment optical coherence tomography (OCT, Zeiss).

Ultrasound as well as the OCT technique is based on beam reflection at optical interfaces. Ultrasound waves or, respectively, coherent light beams (electromagnetic waves) are used for the imaging. Twenty-six patients were examined using the OCT and ultrasound with special emphasis on the corneal thickness and the results compared.

The use of OCT to measure the corneal thickness is a safe method. Both techniques give comparable pachymetry results, whereas the OCT technique shows a tendency for lower values. Statistically significant differences could not be shown.

OCT is a new, non-contact technique for measuring the corneal thickness. Furthermore, this is a method that does not interact with other measurements like keratometry or corneal topography.