Fuch's Heterochromic Iridocyclitis in Iran: Is the Disease Going to Fade Away?

Dear Editor,

There is a diverse group of well-known uveitic entities which are of unknown etiology. Many experts believe that the majority of them are the consequences of unknown infectious pathogens, most probably viral.[1]

Fuch's heterochromic iridocyclitis (FHI) is a well-known entity, which usually presents as a unilateral low-grade inflammation in a white eye with diffuse, stellate keratic precipitates and, mild anterior chamber inflammation, iris atrophy and no posterior synechiae.[23] In addition there is an associated 70% risk of cataracts and 15% risk of glaucoma.[23]

FHI is unique in that polymerase chain reaction (PCR) studies on aqueous samples in several clinical studies has identified the rubella virus as the cause of the entity.[456] Nowadays, FHI is rarely seen in uveitis cases in the United States which is in contrast to developing countries. We assume the reason is the difference in national immunization programs between Western countries and developing countries.

The mumps, measles, and rubella (MMR) vaccine was licensed in the United States in 1971, although it was first used in 1969. In an epidemiologic study at the University of Chicago, it was shown that after vaccination with MMR vaccine, the incidence of the diseases were decreased by almost 30% each decade afterwards.[7] Today, after over 40 years since starting immunization, a patient with FHI younger than 40 years of age is hardly ever seen which supports the efficacy of vaccination in preventing the disease.

MMR vaccination was started routinely as a national health care protocol in Iran since 2005, before which rubella and mumps were not included in the national immunization program.

If we accept the aforesaid scenario, a 30% decrease of the disease in each subsequent decade can be expected, and theoretically after half a century, the disease will disappear with 100% vaccination.

There are many other uveitis entities in which the etiology is unknown. Acute posterior multifocal placoid pigment epitheliopathy is a rare condition in the United States today, although according to the anecdotal data the prevalence of the disease was much higher 20 years before; however at present, it is commonly seen in Iran. A possible underlying infectious etiology which has faded in the West but is still very common in developing countries, such as tuberculosis should be considered.

We believe and hope that a better understanding of the pathogenesis of uveitis disorders will be beneficial in preventing them in near future.