The Corvis ST analysis of underaged versus adults' healthy eyes with comparable tomography detects softer corneas in children and adolescents as opposed to adults

Abstract

This cross-sectional cohort study aimed to analyze whether corneal biomechanics differ between healthy eyes of different age, even if they appear tomographically identical. All volunteers underwent corneal Scheimpflug imaging (Pentacam) and biomechanical examination (Corvis ST, CST both Oculus, Germany). Three groups (G) were formed according to age: (G1) children aged 3–10 years (n = 250, 7.7 ± 1.9 years (mean ± standard deviation)), (G2) adolescents aged 11–20 years (n = 350, 15.3 ± 2.9 years) and (G3) adults (n = 100, 48.7 ± 13.8 years). Main tomographic outcome parameters were: flat anterior (K1F)/posterior (K1B) and steep anterior (K2F)/posterior (K2B) meridians, thinnest corneal thickness (TCT) and maximal anterior keratometry (Kmax). Considering biomechanics, these were deformation amplitude ratio 2 mm (DA ratio 2 mm), integrated radius (IR), Ambrósio Relational Thickness horizontal (ARTh), stiffness-parameter (SP-A1) and corneal velocity at inward applanation (A1 velocity), stress-strain-index (SSI), Corvis Biomechanical Index (CBI), Biomechanical E-Staging (BEST) and the CST-derived non-contact (IOPnct) and biomechanically adjusted intraocular pressure (bIOP). The groups were compared with Kruskal–Wallis one-way ANOVA and Dunn’s post test. The three groups G1–G3 were tomographically comparable (p > 0.05 for K1F/K1B/K2F/K2B/TCT/Kmax). Biomechanically, there was no difference for DA ratio 2 mm and ARTh between G1–G3. Significant differences were found for SP-A1 (G1 < G2< G3, p = 0.0125), IR (G2 < G3, p = 0.0288), A1 velocity (G1 < G2< G3, p = 0.0027), SSI (G2 < G1< G3, p < 0.0001), CBI (G3 < G2< G1, p = 0.001), BEST (G3 < G2< G1, p = 0.0015), IOPnct (G3 < G1< G2, p = 0.0006) and bIOP (G3 < G2< G1, p < 0.0001). There exist small, yet significant biomechanical differences in CST measurements between tomographically comparable healthy corneas in dependence of age indicating biomechanically weaker corneas in children than in adults.