Comparisons of corneal biomechanical and higher-order aberrations between thin normal cornea and Forme Fruste keratoconus

Background To compare the corneal biomechanical parameters and higher-order aberrations (HOAs) of thin normal cornea (TNC) and Forme Fruste keratoconus (FFKC). Methods The data collected between June 2018 and May 2023 at the Eye Hospital Affiliated with Shandong First Medical University were divided into two groups: 26 normal eyes of 26 patients (18–38 years) with the thinnest corneal thickness (TCT) ≤ 500 µm and 26 eyes of 26 patients (14–35 years) with FFKC. Central corneal thickness (CCT) and biomechanical-corrected intraocular pressure (bIOP) were matched by propensity score matching. Scheimpfug imaging (Pentacam) and corneal visualization Scheimpfug technology (Corvis ST) were used to compare the variations in corneal biomechanical parameters and HOAs between the two groups. The receiver operating characteristic (ROC) curve was used to judge the accuracy of significantly different parameters in predicting FFKC. The FFKC diagnostic model was established using the best discriminant function. Results The time of the first applanation (A1T), the velocity of corneal movement during the second applanation (A2V), the time at which the cornea reached the highest concavity (HCT) and the total corneal root mean square (RMS) of the HOA were significantly different between the two groups (P < 0.05). HCT showed good potential for distinguishing between FFKC and TNC. The best discriminant function showed a prediction accuracy of 78.4%. Conclusion This study suggested that the relationship between certain biomechanical properties and HOAs could be valuable for the diagnosis of FFKC.