Interpretation of Variation in Corneal Parameters with Age using Pentacam: A Cross-sectional Study

Abstract

Introduction: Previous equipments used to study cornea were mostly Placido based which could only analyse anterior surface of cornea, while Pentacam is based on elevation based imaging method that helps to study the curvature of cornea, its elevation and thickness profile more accurately. There are numerous studies published to study the thickness of cornea, this study outlines the importance of changes introduced in various corneal parameters with age which in itself is an important factor with possible positive correlation. Aim: To determine various corneal parameters and to interpret the variations in these with increasing age. Materials and Methods: This cross-sectional study included a cohort of 60 healthy patients attending Outpatient Department of Ophthalmology from July 2019 to February 2020. Two sets of values were determined, studied and compared between different age groups. First set of values included, keratometry values in the flat (K1) and steep (K2) and maximal keratometry values of the front surface (Kmax). Second set of values included, Anterior Elevations (AE), Posterior Elevations (PE), PE minus AE from Best Fit Sphere of 8 mm (BFS) and PE from the Best-fit Toric Ellipsoid (BFTE), apex thickness (CCT), pachymetry at the thinnest-point thickness (TCT),average corneal Pachymetry Progression Indices (PPI avg) and average Ambrosio’s Relational Thickness indices (ART avg). Based on age, three groups were created with 20 participants in each, Group A with age 18 to 25 years, Group B with age between 26 and 40 years and Group C with age more than 40 years. Scanning of all study subjects was done using Pentacam. Mann-Whitney U test and Spearman correlation test were used for the statistical analysis. Results: The average age was 21±2.42 years in group A, 30.9±4.3 years in group B and 42.45±1.65 years in group C. When AE, PE and PE-AE values were compared among three age groups, results were highly significant with p-value <0.00001. Thus, the elevation indices from BFS were found to be correlated with age. On comparison of PPI average between group A and B, group B and C values were statistically insignificant (p-values 0.51 and 0.19, respectively).Though in comparison between Group A and C, average corneal PPI avg was found to be of statistical significance (p-value=0.048). Average ART indices (ART avg) was found to produce highly statistically significant results among 3 groups (p-value <0.00001). Conclusion: The corneal parameters are significantly altered from their normative values with age. This study outlines that elevations indices and avg ART values are significantly altered with increasing age.