Tonic pupils in neurosyphilis.

Of 60 patients with tonic pupils, 29 had serologic tests for syphilis. Five patients had positive blood serology and confirmatory tests; four had other manifestations of neurosyphilis and positive CSF serology. All seropositive patients had bilateral tonic pupils with light-near dissociation and denervation hypersensitivity. Of the 10 tonic pupils, only 1 was miotic and 1 dilated. Although tonic pupils tend to become small and bilateral, they should be distinguished readily from Argyll Robertson pupils, which react briskly, not tonically, to near stimuli. Patients with bilateral tonic pupils should have serologic tests for syphilis.