Central Corneal Thickness in Latino Glaucoma Patients and Glaucoma Suspects. Comparison of OCT and Ultrasound Methods of Pachymetry.

Abstract

Purpose : Measuring central corneal thickness (CCT) is important in the management of glaucoma partly because of the potential source of over- or under-estimation on IOP measurement that can be induced by significantly thick or thin corneas. In addition, thin corneas as measured by pachymetry, are among one of the most important risk factors for both development and progression of glaucoma damage. Pachymetry has been increasingly performed with OCT (p-OCT) as compared with the traditional ultrasound (p-US). The objective of this study is to establish a comparison in agreement, accuracy and precision of two methods of pachymetry: p-US versus p-OCT.

Methods : Retrospective study of consecutive cases of patients with glaucoma which clinical information was obtained from the electronic health records of patients visiting a glaucoma center. Complete clinical information and both methods of pachymetry were required for the cases to be included in the study. CCT was measured by p-US and p-OCT in one or two different moments (no longer than 6 months apart). Mean values of pachymetry were compared by paired t-test. Bland-Altman plots were used to assess the agreement between both instruments. The correlations between the variables were also analyzed. A p-value of ≤ 0.05 was considered as statistically significant.

Results : This study analyzed 108 eyes of 54 patients (mean age of 63.24±12.7 years), being predominantly female (55.6%), with POAG (63%). The mean CCT values per eye were significantly different (RE, p-US, 536.9 ± 38.8 μm, p-OCT, 521.17 ± 37.95 μm; p=0.0355; LE, p-US, 539.5 ± 38.7 μm; p-OCT, 522.22 ± 38.42 μm, p=0.0218). In overall analysis of both eyes, the mean difference was 16.53 μm, 95% CI 9.28-23.78 μm. The difference in measurements by US pachymetry and AS-OCT was statistically significant (p < 0.001). RE and LE were highly and significantly correlated with both methods (RE, r=0.81, p=0.0001; LE, r=0.92, p=0.0001). Bland-Altaman analysis is presented in figure 1.

Conclusions : This study confirms other researchers’ findings about a significant difference in measuring CCT by OCT and US, so further investigation is required on precision and accuracy for each method.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.