Keratoconus is a clinical term used to describe a condition in which the cornea assumes a conical shape as a result of noninflammatory thinning and protrusion. Keratoconus is detected clinically by slit-lamp evaluation, which demonstrates stromal corneal thinning. Other clinical signs may include Vogt striae, iron ring, scarring, retroillumination signs such as the 'Charleaux oil droplet reflex,' and/or scissoring on retinoscopy; in subtle cases, the diagnosis may be confirmed by videokeratography. The estimated prevalence of keratoconus ranges from 50 to 230 per 100,000 in the general population, and approximately 6% to 23.5% of reported cases demonstrate familial transmission. Age of onset is at puberty and the disorder is progressive until the third or fourth decade of life, when it usually arrests. It is a major cause of cornea transplantation in developed countries (summary by Li et al., 2006).
For a discussion of genetic heterogeneity of keratoconus, see KTCN1 (148300). [from
OMIM]