Keratoconus (KC) is a progressive ectatic condition of the cornea, and recent evidence suggests that inflammation may have a role in its pathogenesis. KC typically presents itself during the teenage years and progresses until the third and fourth decades of life. In two population based studies, the reported prevalence was 4.8% in 6- to 21-year-olds and 0.8% in 14- to 29-year olds. Even the behavior of the disease varies at different ages, and the risk of faster progression is higher in younger people. In 1 study, 27.8% of those aged younger than 15 years, compared with 7.8% of the adults, had advanced disease. Patients with Down syndrome have a higher likelihood of developing KC, hypothesized to be related to the candidate genes for KC residing on chromosome 21. A study of 27 Down syndrome patients reported a prevalence of 21.1% (11 eyes) for subclinical topographic KC.
