12 years of age or older

Diagnosis of keratoconus, FFKC, post-LASIK ectasia, or pellucid marginal degeneration or forme fruste pellucid marginal degeneration (FFPMD).

Diagnosis of FFKC

History of Radial Keratotomy with fluctuating vision

Ability to provide written informed consent

Likely to complete all study visits

Minimum corneal thickness of at least 300 Measured by ultrasound or Pentacam

At least 6 months since last corneal surgery (Intacs/PRK/LASIK/Epi-LASIK/LASEK)

Cross-linking of Corneal Collagen (CXL) With Ultraviolet-A in Asymmetric Corneas