Doyne lecture. Heterochromic iridocyclitis

Fuchs' heterochromic iridocyclitis is a rare but significant cause of visual impairment. This form of uveitis is misdiagnosed more than any other in the entire field of uveitis. This is particularly true among brown-eyed individuals in whom gross heterochromia may not be diagnosed for many years. The clinical presentation of Fuchs' heterochromic iridocyclitis may include a number of generally unrecognised variants among which are Koeppe nodules, transient synechia formations, and blood-filled cysts. Recently the relationship of heterochromic iridocyclitis to posterior inflammatory lesions, such as those of toxoplasmosis, has been explored. Although the disease was once thought to be a degenerative or trophic disorder, current investigations reveal that it is a true inflammation of immunologic origin. The disorder may be related to a depression of suppressor T-cell activity. The aetiology of the disease is still obscure, but in some cases an association with simple heterochromia has been found among families in whom multiple members are affected by either simple heterochromia or Fuchs' heterochromic iridocyclitis. Corticosteroid treatment of Fuchs' heterochromic iridocyclitis is not effective and should be reserved for those patients in whom inflammatory products obstruct the visual axis. Most patients should be treated by observation alone. Cataract and glaucoma are the most important complications. Treatment of the glaucoma is particularly difficult and often unsuccessful.