Keratoconus is a degenerative disease entity characterized by conical shape ectasia of the cornea. progressive conical deformation of the cornea leads to substantial astigmatism. Patients who are at an advanced stage of ectasia are often led to corneal transplant or other treatments, which essentially aim at correcting the refractive error and not in treating the ectasia. The top of the protruding cone that corneal configuration may be close to the visual axis or below and nasal of that. The disease manifests during adolescence, followed by slow progressive course, although it is possible to stabilize anytime. In 85% of cases both eyes are affected, but the severity of the attack can present significant asymmetry.

Often in keratoconus a positive family history is present. Prevelance of keratoconus varies greatly worldwide.The reported prevalence of keratoconus varies widely depending upon the geographic location, diagnostic criteria used, and the cohort of patients selected. Environmental factors may contribute to the wide variation in prevalence.

the Middle East have higher prevalence than locations with cooler climates and less sunshine

Inclusion Criteria:

1. persons attending refractive surgery centers in Asssiut.
2. patients found to have keratoconus are included , based on history , clinical examination and corneal topography

Exclusion criteria :

1. patients not attending those refractive surgery centers.
2. patients attending these centers but not diagnosed to be keratoconus .
3. Pregnancy or breastfeeding

patients with keratoconus in people attending refractive surgery