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 ... 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).
Rabinowitz et al. (1992) studied a family segregating autosomal dominant keratoconus over 3 generations. Of 8 affected individuals, 2 had undergone penetrating keratoplasty; the histopathologic findings were consistent with keratoconus, including fragmentation of the Bowman membrane, stromal thinning, ... Rabinowitz et al. (1992) studied a family segregating autosomal dominant keratoconus over 3 generations. Of 8 affected individuals, 2 had undergone penetrating keratoplasty; the histopathologic findings were consistent with keratoconus, including fragmentation of the Bowman membrane, stromal thinning, subepithelial fibrosis, and an iron line when stained with Prussian blue. In 4 of the 6 remaining patients, biomicroscopy revealed a cone and a Fleisher ring, and topographic maps generated using high-resolution computer-assisted videophotokeratoscopy demonstrated central steepening consistent with a nipple-type cone in all 6, including 2 family members who had normal slit-lamp findings and no change detected on corneoscopy.