Agreement Between Central Corneal Thickness Measured by Ultrasound Pachymetry and Minimal and Central Thicknesses Determined Using the Pentacam

Abstract

Purpose: : to examine agreement between central corneal thickness measured by ultrasound pachymetry (CT-U) and central (CT-P) and minimum (MT-P) thicknesses determined using the pentacam.

Methods: : corneal thickness measurements were made using the two instruments in 131 eyes with primary open-angle glaucoma. Agreement between the instruments was assessed by calculating intraclass correlation coefficients (ICC) and the Passing-Bablok method was used to establish the presence of systematic and/or proportional biases.

Results: : ICC were 0.98 (95%CI: 0.9-0.99) for the comparison CT-P vs MT-P, 0.79 (95%CI: 0.71-0.85) for CT-U vs CT-P and 0.77 (95%CI: 0.69-0.83) for CT-U vs MT-P. Passing-Bablok regression revealed a systematic bias of 2 mmHg (95%CI: 2-14) for CT-P vs MT-P, both a systematic bias of 93.28 mmHg (95%CI: 22.81-182.08) and a proportional bias (B=1.16; 95%CI: 1.03-1.32) for CT-U vs MT-P and a systematic bias of 81.71 mmHg (95%CI: 17.94-161.43) along with a proportional bias (B=1.14; 95%CI: 1.03-1.18) for CT-U vs MT-P.

Conclusions: : agreement between minimal and central thicknesses determined with the pentacam is excellent with only a 2 mmHg systematic bias detected between the two measurements. In contrast, agreement between central corneal thickness measured by ultrasound pachymetry and the Pentacam-determined thicknesses can only be described as good since both systematic and proportional biases were observed.

Keywords: intraocular pressure