Comparison of Pentacam data in patients with diagnostic criteria for keratoconus in only one eye

ABSTRACT Purpose: To compare data extracted from the Pentacam exam in patients with keratoconus in one eye and form fruste keratoconus in the other eye. Setting: Private clinic in São Paulo, Brazil. Design: Retrospective review. Methods: This study reviewed charts of patients with keratoconus in one eye and forme fruste keratoconus (FFKC) in the other, from January to December 2019. All subjects were evaluated with a rotating Scheimpflug imaging system. Twenty-two eyes of 11 patients were compared, and only one eye had established diagnostic criteria for keratoconus. Given this, 38 variables obtained through Pentacam were compared. Results: In eyes with keratoconus, several parameters exhibit significant alterations compared to those with FFK eyes. Notably, Belin elevation and posterior and total densitometry remain consistently significant, indicating early changes in mild forms of the disease and progression over time. Additionally, indicators such as IVA, KI, IHD, posterior elevation of BFTA, and R min demonstrate notable changes in FFKC eyes. Among these, the index of height decentration (IHD) stands out, with the highest alteration rate of 81.8% in FFKC patients. Furthermore, parameters like the D index (total), EI posterior, and Maximum posterior elevation with BFS, IHD, Kmax, and Q value demonstrate high accuracy, sensitivity, and specificity in distinguishing FFKC from control eyes. Kmax, Belin Ambrósio Posterior Elevation, IHD, and posterior elevation of best-fit reference sphere (BFS Posterior Elevation) emerge as the most altered parameters in FFKC. Conclusion: We considered the IHD, the BFS posterior elevation, Kmax, asphericity, Belin-Ambrósio display, and decentration of the thinnest point as sensitive indicators for initial keratoconus cases, IHD being the most accurate of them.