Interstitial keratitis in untreated latent (late) syphilis.

Untreated latent syphilis with interstitial keratitis is not uncommon in the older age group who may present with refractive problems. It is important to investigate these patients with a full range of serological tests for syphilis to determine whether they have been treated adequately in the past. If there is evidence of untreated latent syphilis, examination of the cerebrospinal fluid is important to exclude asymptomatic neurosyphilis for which intensive systemic therapy in hospital is indicated. If there is no evidence of central nervous system involvement a course of penicillin is still indicated, but may be given on an outpatient basis. This is illustrated by the histories of six patients who presented to The Royal Victorian Eye and Ear Hospital between 1962 and 1979.