The anterior surface of the lens can assume an abnormal shape, either conical (lenticonus) or spherical (lentiglobus). Clinically, an “oil droplet” red reflex is present. Anterior lenticonus may be unilateral or bilateral. Bilateral anterior lenticonus is usually associated with Alport syndrome, which is typically an autosomal dominant disease and is characterized by hemorrhagic nephritis, deafness, anterior polar cataract, retinal flecks, and retinal and iris neovascularization, in addition to anterior lenticonus. Mutations in type IV collagen genes have been described in some forms of Alport syndrome.
Histology reveals thinning of and dehiscences in the anterior lens capsule, a decrease in the number of anterior lens epithelial cells, and bulging of the anterior cortex. Ultrastructural alterations of lens capsule collagen and immunohistochemical abnormalities in type IV collagen have been observed.