Diagnostic ability of the corneal anterior and posterior surface area calculated by corneal modelling approach in early stage keratoconus patients

Purpose: To investigate the discrimination ability of the corneal anterior and posterior surface area between patients with keratoconus stage 1 and normal individuals. Methods: In this retrospective study, 116 eyes of 116 normal individuals and 366 eyes of 366 keratoconus patients were included. Keratoconus patients were divided into six groups according to the topographic keratoconus classification of Pentacam. Anterior and posterior surface data of sagittal (SM) and elevation maps (EM) were exported from Pentacam, and human corneal models were created employing the software utilizing the PyVista module of Python programming language. The anterior and posterior corneal surface area (a-CSA and p-CSA) of SM and EM were calculated by the software ranging from central 3 to 8mm diameter. Results: Anterior and posterior CSA values were higher in KC patients compared to normal individuals (p < 0.001). The p-CSA for SM and EM measured at the central 3mm was higher in patients with KC-1 compared to normal eyes (p = 0.002, p = 0.005, respectively), For both maps, a-CSA and p-CSA measured at the central 4 and 5mm were higher in KC-1 compared to normal individuals (p < 0.05). The highest area under the curve (AUC) values in the diagnosis patients with KC-1 were obtained from 3mm p-CSA for SM (AUC: 0.8338), 3mm p-CSA for EM (AUC: 0.7999), 4mm p-CSA for SM (AUC: 0.8531), 4mm p-CSA for EM (AUC:0.7948), 5mm p-CSA for SM (AUC: 0.8455), 5mm p-CSA for EM (AUC:0.7614). Conclusion: The corneal surface area as a parameter, especially for central 3, 4, and 5mm, has a discrimination ability in diagnosing keratoconus disease and distinguishes normal eyes from KC-1 eyes.