Keratoconus is a noninflammatory progressive corneal thinning disorder resulting in mixed myopia and irregular astigmatism. Characteristic features include stromal thinning, Vogt striae, Fleisher ring, and scissoring of the retinoscopic reflex with a fully dilated pupil. Symptoms usually develop in the second decade and are likely to progress in the third decade, whereas progression slows after age 30 years. The progression of keratoconus may result in severe visual impairment and some affected individuals require cornea transplantation. The prevalence of keratoconus is about 1 in 2,000 in Caucasian populations, and is a leading cause for cornea transplantation in developed countries (summary by Tang et al., 2005).
For a discussion of genetic heterogeneity of keratoconus, see KTCN1 (148300). [from
OMIM]