Very Low Prevalence of Keratoconus in a Large Series of Vernal Keratoconjunctivitis Patients

PURPOSE: To evaluate the prevalence of keratoconus (KC) and other corneal abnormalities by means of videokeratography and tomography in a large series of patients affected by vernal keratoconjunctivitis (VKC). DESIGN: Cross-sectional study. METHODS: SETTING: Single-center children’s hospital. STUDY POPULATION: A total of 651 consecutive patients with VKC and a control group of 500 were prospectively recruited between May 1, 2012 and September 30, 2013, with a minimum follow-up of 12 months. OBSERVATION PROCEDURE: All patients were evaluated by means of a Scheimpflug camera combined with a Placido corneal topographer. Keratoconus, suspected keratoconus, or its absence were determined in each patient. The corneal symmetry index of front (SIf) and back curvature (SIb), shape indices, and thicknesses were compared between the 2 groups. MAIN OUTCOME MEASURES: Prevalence of keratoconus and corneal indices modifications. RESULTS: Five out of 651 patients (0.77%) demonstrated topographic signs of KC. Two of them were bilateral. All patients were older than 7 years of age, and the mean age was 11.54 years. Four other patients (0.61%) were classified as KC suspects by the screening program. Of 304 patients older than 11 years (mean age 14.4 years), 4 (1.32%) were found to have KCN, and 4 (1.32%) were KC suspects. The corneal indices of patients in the VKC group were extremely similar to those in the control group. (P > .05). CONCLUSIONS: The prevalence of KC in our patient population, compared with previous reports in the literature, is much lower. The similar corneal indices in both groups suggest the absence of permanent corneal deformation due to VKC.