J Korean Ophthalmol Soc.  2021 Jul;62(7):904-909. 10.3341/jkos.2021.62.7.904.

Comparison of Central Corneal Thickness Measured by Tono-pachymetry and Ultrasound Pachymetry

• Park HY
• Shin HY

• KMID: 2518492
• DOI: http://doi.org/10.3341/jkos.2021.62.7.904

Abstract

Purpose
We compared the accuracy of central corneal thickness (CCT) measurements according to CCT measured by noncontact Tono-pachymetry and ultrasound pachymetry (USP).
Methods
CCT was measured in 90 eyes of 90 subjects by two optometrists. The CCT measurements were compared and the correlations between the measurements were analyzed. To evaluate whether the measurements varied depending on CCT, the subjects were classified into three groups according to CCT (group 1: thin thickness group; group 2: medium thickness group; and group 3: thick thickness group). The differences in CCT obtained by the two devices (△CCT = Tono-pachymetry-USP) were compared and analyzed among the three groups.
Results
The average CCT measurements by Tono-pachymetry and USP were 523.26 ± 32.93 μm and 527.08 ± 37.33 μm, respectively. CCT by Tono-pachymetry was significantly thinner than by USP (△CCT= -3.82 ± 15.34, p = 0.020). The two measurements were strongly correlated (r = 0.912, p < 0.001). The △CCT values were 5.40 ± 12.13 μm in group 1, -6.37 ± 15.07 μm in group 2, and -10.50 ± 14.39 μm in group 3 (p < 0.001).
Conclusions
CCT measured by tono-pachymetry was thinner on average compared to the value measured by USP and the differences in measurements between the two devices were different according to CCT. The thinner the CCT, the thicker the measurement, and the thicker the CCT, the thinner the measurement. Therefore, this trend should be considered when interpreting tono- pachymetry results in clinical practice.

Keyword

Central corneal thickness, Tono-pachymetry, Ultrasound pachymetry