Aniridia

The term aniridia is a misnomer because iris tissue is usually present, although it is hypoplastic.

Two thirds of the cases are dominantly transmitted with a high degree of penetrance. The other one third of cases are sporadic and are considered to be new mutations. The condition is bilateral in 98% of all patients regardless of the means of transmission and is found in approximately 1/50,000 persons.


Aniridia is a panocular disorder and should not be thought of as an isolated iris defect. Macular and optic nerve hypoplasia are commonly present and lead to decreased vision and sensory nystagmus. The visual acuity is measured as 20/200 in most patients, although the vision may occasionally be better. Other ocular deformities are common and may involve the lens and cornea. The cornea may be small, and a cellular infiltrate (pannus) occasionally develops in the superficial layers of the peripheral cornea. Clinically this appears as a gray opacification. Lens abnormalities include cataract formation and partial or total lens dislocation. Glaucoma develops in as many as 75% of individuals with aniridia.

One fifth of sporadic aniridic patients may develop Wilms tumor.Of particular interest is the association of aniridia, genitourinary anomalies, mental retardation, and a partial deletion of the short arm of chromosome 11. Among individuals thus affected, the appearance of Wilms tumor is more common. It is thought that only patients with sporadic aniridia are at risk for developing Wilms tumor, although Wilms tumor has occurred in a patient with familial aniridia. Wilms tumor usually presents before the 3rd yr. Therefore, these children should be screened using renal ultrasonography every 3–6 mo, until approximately age 5 yr of age.

Retinitis Pigmentosa

The name is actually a misnomer because retinitis pigmentosa is not an inflammatory process. Most cases are due to a mutation in the gene for rhodopsin, the rod photopigment, or in the gene for peripherin, a glycoprotein located in photoreceptor outer segments..

This is a general term for a disparate group of rod and cone dystrophies characterized by progressive night blindness, visual field constriction with a ring scotoma, loss of acuity, and an abnormal electroretinogram (ERG). It occurs sporadically or in an autosomal recessive, dominant, or X-linked pattern. Irregular black deposits of clumped pigment in the peripheral retina, called bone spicules because of their vague resemblance to the spicules of cancellous bone, give the disease its name.

Vitamin A (15,000 IU/day) slightly retards the deterioration of the ERG in patients with retinitis pigmentosa but has no beneficial effect on visual acuity or fields. Some forms of retinitis pigmentosa occur in association with rare, hereditary systemic diseases (olivopontocerebellar degeneration, Bassen-Kornzweig disease, Kearns-Sayre syndrome, Refsum's disease). Chronic treatment with chloroquine, hydroxychloroquine, and phenothiazines (especially thioridazine) can produce visual loss from a toxic retinopathy that resembles retinitis pigmentosa.