Comparison of Corneal Epithelial Thickness Mapping using Two Different Optical Coherence Tomography

Doi: 10.36351/pjo.v42i3.2241

Abstract

Purpose:  To assess agreement between corneal epithelial thickness maps obtained with MS-39 and Optovue Avanti OCT devices in healthy eyes, and to ascertain if their measures are interchangeable.

Study Design:  Descriptive comparative study.

Place and Duration of Study:  Amanat Eye Hospital, Rawalpindi from May 2025 to July 2025.

Methods:  In this study, 23-eyes were scanned with MS-39 and Optovue. Central (0-2mm), paracentral (2-5mm) and mid-peripheral (5-7mm) epithelial thickness measurements were taken. The Shapiro-Wilk test was used to evaluate the normality of data. The pair measurements were compared using Wilcoxon signed-rank test. Reliability was determined with intraclass correlation coefficient (ICC) and agreement with Bland-Altman analysis. A p<0.05 value was considered statistically significant.

Results:  Majority of variables were not normal. The Wilcoxon analysis revealed systematic differences between the devices. MS-39 recorded greater readings in paracentral and peripheral sectors, while Optovue reported higher central values. The overall agreement was good when averaging several measurements [ICC (3, K) = 0.823] and moderate for a single measurement [ICC (3,1) = 0.699]. Zone and sector-based analysis revealed highest agreement in the paracentral region, moderate agreement in the central zone, and the lowest in the mid-peripheral region.

Conclusion:  Both MS-39 and Optovue provide reliable epithelial thickness measurements, but their results are not interchangeable. Optovue tends to overestimate central thickness compared to MS-39, while MS-39 yields higher peripheral values. Device-specific reference data should therefore be used in clinical practice, and switching between devices is not recommended in longitudinal follow-up or surgical planning.