Congenital Rubella Cataract

Rubella Cataract
Definition: The rubella induced cataract is a congenital cataract that follows German measles infection (rubella) in the mother. Exposure usually occurs in the first or second trimester of pregnancy. Cataract is one of many manifestations of the congenital rubella syndrome.
Incidence/Prevalence: About 100,000 cases of congenital rubella syndrome occur in the world each year. Rubella accounts for about 5-25% of pediatric cataracts in India. The incidence of rubella cataracts plummeted after introduction of the vaccine circa 1970. The frequency of cataracts in congenital rubella syndrome is about 10-15 % or slightly less than rubella retinopathy. During the U.S. epidemic of 1963-4, about 12.5 million people were infected and about 10,500 cases of congenital rubella occurred.
Etiology: Norman McAlistair Gregg linked congenital cataracts with maternal rubella infection in 1941. Rubella virus is an enveloped RNA virus. Congenital infection persists through pregnancy and may be recovered from patients as old as 2 years and 11 months of age (Menser et al. 1967, Lancet ,19: 387).
Clinical Findings: The cataracts are often bilateral, usually central, and may be lamellar, nuclear or membranous. Occasionally resorption of the cataractous center results in a clear pupillary axis. Infection early in pregnancy is associated with a worse cataract than infection of later onset. Other ocular features include nystagmus, strabismus, microphthalmos, corneal opacities, retinopathy, glaucoma and a small pupil that is difficult to dilate. The classical triad of congenital rubella syndrome is comprised of sensorineural hearing loss, ocular abnormalities and congenital heart disease.
Gross Morphology: Frequently a dense cataract is seen centrally or anteriorly. In the photography there appears to be a more clear zone posterior to the angled white opacity.

Histopathology: Histologically, the lens is usually microspherophakic. Frequently, there is accompanying liquefaction and necrosis of lens. The iris is often bowed forward by the lens. In the accompanying gross and microscopic figures, the lens appears small and cataractous. The triangular opacity is prominent anteriorly and seen both in the gross and microscopic examination. Retained lens fiber nuclei are present. The nuclei may appear pyknotic or karyorrhexic. At white arrow #1 faded nuclei are apparent. Rubella virus may be cultured from surgically removed lenses up to ~3 years of age. PCR techniques may be more sensitive. (Indian J Med Res. 2007 Jan;125(1):73-8)

A non-granulomatous uveitis affecting particularly the iris has been described by Font and Zimmerman.
Treatment: Prevention through immunization of children and women before they become pregnant is the best approach. Cataract removal can be performed.