Study Hypothesis: Former investigators indicated that keratoconus has a negative impact on vision-specific quality of life. This study attempts to confirm this statement and assess whether cross-linking and cross-linking combined with photorefractive keratectomy improve vision-specific quality of life, in a sample of keratoconus patients with 3-years follow-up.

Inclusion Criteria:

• be diagnosed and classified as stage 1 keratoconus according to the Amsler-Krumeich classification system for keratoconus
• present progressive keratoconus in consecutive corneal topographies, and/or changes in their refractive power.

Progressive keratoconus was defined when any of the following criteria was met for a period of 24 months:

• an increase of 1.00 diopter (D) or more in the steepest keratometry measurement
• an increase of 1.00 D or more in manifest cylinder
• an increase of 0.50 D or more in manifest refraction spherical equivalent.

Exclusion Criteria:

• glaucoma
• suspicion for glaucoma
• IOP-lowering medications
• central corneal thickness (CCT) less than 400μm
• K-readings more than 60D
• history of herpetic keratitis
• corneal scarring
• severe eye dryness
• pregnancy or nursing
• current corneal infection
• or underlying autoimmune disease KG members were further sub-divided into CxL and tCxL groups, according to their eligibility for treatment with CxL or CxL with tPRK. In order to be eligible for tCxL, group participants should, additionally, have CCT above 450μm.