Improving the diagnostic efficiency of forme fruste keratoconus by a new combined model with Fourier parameters and...

To explore a new method to improve the diagnostic efficiency of forme fruste keratoconus (FFKC) using the combination of Fourier parameters and corneal epithelial aberrations.

Prospective, case-control analysis.

This prospective study enrolled 55 FFKC patients and 68 healthy subjects. The same experienced operator performed Casia 2 (Tomey, Nagoya, Japan) and MS-39 (CSO, Florence, Italy) examinations to obtain Fourier parameters and corneal epithelial aberrations within the central 6 mm of the cornea. Independent-samples T tests were applied to compare statistical differences between the two groups. Significant variables were selected through dual logistic regression analysis with a stepwise method. The areas under the receiver operating characteristic curves (AUROC) were calculated to estimate the diagnostic ability for each parameter and the combined model, and the Youden index was used to determine the cut-off value. Delong test was performed to compare the differences among the AUROC in different conditions.

The spherical component in Fourier parameters of the posterior surface of the cornea (P = 0.002), the asymmetry of the posterior surface of the cornea (P < 0.001), the higher-order irregularity in Fourier parameters at the posterior surface of the cornea (P = 0.026), and corneal epithelial Z (3, ±1) coma (P = 0.035) were selected as explanatory variables. The combined model demonstrated significantly improved diagnostic efficiency with the highest AUROC value of 0.95 (sensitivity, 0.855; specificity, 0.897; cut-off, 0.400). And the AUROC of the combined model was significantly different from that of the single parameter (P < 0.05).

The integration of Fourier parameters and corneal epithelial aberrations holds potential in enhancing the diagnostic efficacy of FFKC, thus serving as a valuable reference for future clinical applications.