Comparison Of 5 Different Pachymetry Devices For Measuring The Central Corneal Thickness

Both optical non-contact methods and ultrasound contact pachymetry can be used to determine corneal thickness. The present study compares five different non-contact measurement methods

This prospective study included 56 eyes of 28 subjects aged 19 to 67 years. The measurements were taken on both eyes.

The following devices were used: Non-Contact Tonometer (NCT), Corvis® (C), IOL-Master® (IOLM), Pentacam® (P) and anterior segment OCT (OCT). The respective differences between the different devices were determined and compared.

The corneal thicknesses were measured between 451µm (min) and 636µm (max). Comparing the different devices with each other resulted in the following differences in average and their standard deviation: 

IOLM-P: 6,43(±10,46), IOLM-C: 7,09(±5,57), IOLM-NCT: 6,59(±5,65), IOLM-OCT: 6,88(±5,51), P-C: 7,63(±8,38), P-NCT: 7,30(±9,91), P-OCT: 7,77(±9,62), C-NCT: 7,89(±4,37), C-OCT: 7,07(±5,46), NCT-OCT: 10,42(±5,59).

We calculated the interrater reliability using the interclass correlation coefficient. The result shows high correlation according to Koo/Li between the measurment results of the devices (ICC=0.992).

The corneal thickness can be reliably determined with all of the devices we tested. No device has to be prefered for reasons of precision or other parameters such as cost or handling of the device.