ASSESSMENT OF AGREEMENT AMONG THREE MODALITIES FOR CENTRAL CORNEAL THICKNESS MEASUREMENT: ULTRASOUND PACHYMETRY, AS OCT, AND SPECULAR MICROSCOPY

Abstract

The cornea plays a critical role in maintaining normal visual function. There are several important clinical parameters such as central corneal thickness (CCT), which is used to diagnose glaucoma, intraocular pressure measurement, refractive surgical planning and other corneal diseases. However, due to variation in measurement results provided by different instruments for determining the thickness of the cornea, it is important to evaluate their correlation and clinical interchangeability. This hospital-based cross-sectional study involved 355 participants above 40 years of age with clinically healthy corneas who visited the Ophthalmology OPD. One way ANOVA followed by Tukey post hoc test was used for the analysis, where a p-value less than 0.05 was considered as statistically significant. The average age of the study population was 48.64 ± 7.01 years, and there were 56.6% females in the group. Ultrasound Pachymetry always provided the highest average value of CCT (524.66 ± 25.50 µm) followed by AS-OCT (512.54 ± 25.08 µm) and Specular Microscopy (505.35 ± 25.14 µm). Significant differences were noted between all three measurement methods for both eyes (ANOVA, p < 0.001). Pairwise comparison revealed that the maximum average difference was between Ultrasound Pachymetry and Specular Microscopy (19.31 µm), while the minimum one was between AS-OCT and Specular Microscopy (7.19 µm), and all differences were statistically significant (p < 0.001). Though Ultrasound Pachymetry, AS-OCT and Specular Microscopy showed a reliable measurement of central corneal thickness, there were some significant systematic differences among these three modalities. Ultrasound Pachymetry gave the highest values and is considered the clinical gold standard. AS-OCT and Specular Microscopy are reliable non-contact methods, yet they cannot be used interchangeably with Ultrasound Pachymetry when serial follow-up of a patient is necessary...