Vitreous syphilis antibody testing could aid in diagnosing syphilitic uveitis
FEB 14, 2023
This prospective case-control study evaluated the sensitivity and specificity of syphilis antibody testing in vitreous samples in order to determine its feasibility as a diagnostic test for syphilitic uveitis.
Nineteen patients (35 eyes) with positive syphilis serology and 19 controls with negative syphilis serology were included. Syphilis serology was used as the gold standard for testing. Positive serology included testing with a nonspecific treponemal test as well as a specific treponemal antibody test, and each patient also had a vitreous tap. Patients underwent clinical assessment, and if the serology was positive patients were treated and subsequently monitored.
Fourteen patients were defined as group 1A (definite syphilis uveitis with positive serology); nearly all eyes had chorioretinitis and retinal vasculitis. No cases had a posterior placoid lesion. All patients in Group 1A improved with treatment. Five patients were defined as group 1B (positive syphilis serology, but clinical findings were not consistent with syphilis or the patient didn’t respond to penicillin). Group 2A was defined as having negative syphilis serology but positive vitreous syphilis antibodies, and group 2B had negative syphilis serology as well as negative syphilis vitreous syphilis antibody. The most sensitive test for syphilis antibodies in the vitreous was enzyme immunoassay (EIA; 90.9%), followed by rapid plasma regain (80.0% sensitivity). Both the EIA and the fluorescent treponemal antibody-absorption tests had 100% specificity.
The study used serology as the gold standard. Testing always has some limitations, as there can be false-positive and false-negative results. Also, because of the small sample size, the study may be underpowered.
The results indicate that vitreous syphilis antibody testing is a viable mechanism to confirm syphilitic uveitis, and may increase the accuracy of the presumptive diagnosis.
Financial Disclosures: Dr. Ashleigh Laurin Levison discloses relationships with AbbVie (Lecture Fees/Speakers Bureau); Clearside Biomedical, Santen (Consultant).