Congenital Aphakia

Congenital aphakia is a rare anomaly that can be subdivided into 2 forms: primary and secondary. Histologically, the lens is absent in primary congenital aphakia. The histologic findings of secondary congenital aphakia depend on the underlying etiology. Primary congenital aphakia results from failed induction of the surface ectoderm during embryogenesis and has been associated with mutations in the PAX6 gene and severe ocular and systemic developmental anomalies. In secondary congenital aphakia, the lens has developed but has been resorbed or extruded before or during birth. This form of aphakia is often associated with congenital infections, such as congenital rubella.

Lens Coloboma

A lens coloboma is characterized by a notch in the lens, typically in an inferonasal location. This congenital anomaly is characteristically associated with ciliary body coloboma and likely occurs secondary to the focal absence or abnormal development of zonular fibers.

Anterior Lenticonus (Lentiglobus)

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.

Posterior Lenticonus (Lentiglobus)

Posterior lenticonus is characterized by a spherical deformity of the posterior surface of the lens (Fig 9-3). Clinically, an “oil droplet” red reflex is seen. Posterior lenticonus usually occurs as a sporadic, unilateral anomaly and is associated with congenital cataract. Other, rare ocular associations include microphthalmos, microcornea, persistent anterior hyaloid vasculature, and uveal colobomas. Posterior lenticonus may also occur as a part of Alport syndrome and the oculocerebrorenal syndrome of Lowe. The oculocerebrorenal syndrome of Lowe is an X-linked condition characterized by systemic acidosis, renal rickets, hypotonia, and congenital cataracts, which histologically display focal, internally directed excrescences of the lens capsule.

Inflammations

Phacoantigenic Uveitis

Also known as phacoanaphylactic endophthalmitis or lens-induced granulomatous endophthalmitis, this type of lens-induced intraocular inflammation is mediated by IgG immunoglobulins directed