Clinical and Subclinical Keratoconus Cohort Study

Inclusion criteria:

1. Inclusion criteria for suspected keratoconus 1.1 Both eyes did not meet the diagnostic criteria for keratoconus, and the included eyes met the criteria 1.1.1 BCVA≥1.0 1.1.2 No obvious abnormal signs under slit lamp; 1.1.3 At least one abnormal corneal topography feature: abnormal anterior corneal surface (KISA>60%); Asymmetric collar with or without meridional tilt (I-S >1.4D); Abnormal increase of corneal curvature (Km>47.2D); The posterior surface of the cornea was abnormally elevated (PTE>11μm).

   1.1.4 1.6≤BAD-D \< 2.6 in Pantacam. 1.2 Patients aged 4 years or older. 1.3 informed consent was obtained from patients. If the patient was younger than 18 years of age, the patient and guardian provided written informed consent.

2. Inclusion criteria for subclinical keratoconus:

   2.1 The contralateral eye was diagnosed with keratoconus, and the included eye met the following criteria: 2.1.1 BCVA≥1.0 2.1.2 No obvious abnormal signs under slit lamp; 2.1.3 BAD-D \< 2.6 in Pantacam. 2.2 Age ≥ 4 years old. 2.3 informed consent was obtained from patients. If the patient was younger than 18 years of age, the patient and guardian provided written informed consent.

3. Keratoconus inclusion criteria:

3.1 History of myopia and astigmatism, BCVA≤1.0 3.2 Slit-lamp examination reveals at least one sign: corneal thinning, conical protrusion, Vogts striae, Fleischers rings, or anterior stromal scarring.

3.3 abnormal corneal topography features, such as asymmetric bow tie, subtemporal steeping, abnormal thickness distribution, and reduced minimum thickness, with BAD-D≥2.6 in Pantacam.

3.4 Age ≥ 4 years old. 3.5 Informed consent was obtained from patients. If the patient was younger than 18 years of age, the patient and guardian provided written informed consent.

Exclusion criteria:

1. Patients with a history of ocular surgery and significant corneal scarring.
2. Patients who could not understand or cooperate with the examination and follow-up.