To investigate the variation in backscattering with depth between forme fruste keratoconus (FFKC), keratoconus, and normal eyes; to determine the backscattering changes in the characteristics of keratoconus progression; and to explore the diagnostic value of backscattering in FFKC.

To investigate the variation in backscattering with depth between forme fruste keratoconus (FFKC), keratoconus, and normal eyes; to determine the backscattering changes in the characteristics of keratoconus progression; and to explore the diagnostic value of backscattering in FFKC. A Scheimpflug corneal tomography image and caliper tool were used to obtain backscatter at every 2% depth at the thinnest point of the cornea, with the measured values expressed in grayscale units (GSU).

Inclusion Criteria:

1. BCVA <20/20 and a history of myopia or astigmatism;
2. presence of any of the following positive signs on slit lamp examination: corneal stromal thinning, cone-shaped anterior protrusions, Fleischer's ring, Vogt's striae, epithelial or subepithelial scarring;
3. abnormal corneal topography (maximum keratometry (K) value of >47.2 diopters (D), bow-tie pattern with skewed radial axes, or inferior-superior asymmetry(3-mm I-S keratometric difference >1.4 D).

Exclusion Criteria:

1. Patients with severe corneal scarring that affected light scattering and density maps showing "black holes" 2.Participatients with other corneal diseases 3. Eyes that have undergone surgery or trauma 4. Eyes with corneal dystrophy

-

The study was performed on patients with keratoconus and healthy participants admitted to Tianjin Eye Hospital from January 2020 to December 2022.