It’s 2023, a new year and a new opportunity for all of us but there’s one thing that some members of the Media MICE team will never change and that’s their obsession with strange ocular conditions. In particular, syphilis, which we can all agree is not your usual cup of tea…
Ocular syphilis remains a poorly understood condition and it is often associated with conditions like HIV that suppress the body’s immune system, in fact, these two diseases are often closely associated. Syphilis first manifests in the primary infection site, usually around the genitals, and then evolves into secondary syphilis where symptoms of the condition then spread throughout the body. This can affect the eyes in a number of ways, for example, a generalized maculopapular or pustular rash is characteristic of secondary syphilis and it can affect the eyelids by causing blepharitis and madarosis.1
Syphilis – The Great Imitator
Posterior segment involvement usually occurs in late secondary syphilis and a number of conditions can occur during this stage including vitritis, necrotizing retinitis, chorioretinitis, retinal vasculitis, and optic neuritis. Uveitis, inflammation of the middle layer of the eye, is often most associated with the anterior segment when it comes to ocular syphilis, however, it can manifest as a posterior complication too. Research literature on the subject has been lacking though, so we dived in and found a comprehensive and fascinating study from China that really sheds light on the issue.1
Demographic, Clinical and Laboratory Characteristics of Ocular Syphilis: 6-Years Case Series Study From an Eye Center in East China is one of those studies that does exactly what it says in the tin and it was only published last year. Drawn up by a group of researchers based in Hangzhou, the capital of Zhejiang Province China, the study examined a total of 2,562 syphilis cases from January 2016 to December 2021. Detailed medical records including systemic and ophthalmic medical history, as well as a complete ophthalmic examination were considered as part of the study.
What makes this study particularly stand out is its comprehensive consideration of imaging technology. This included color fundus photography, B-type ultrasound, fundus fluorescein angiography (FFA), and spectral domain optical coherence tomography (SD-OCT). Laboratory tests of serum and cerebrospinal fluid (CSF) samples, as well as visual field tests, and orbital or cranial MRI in cases with suspected optic neuritis or optic atrophy, were also collected and analyzed.
Posterior Uveitis – Surprisingly Common
All in all, 131 cases with ocular syphilis were discovered while only 6 cases had a medical history or clinical manifestations of systemic syphilis, including dermal rashes in 4 cases, syphilitic epilepsy, and dementia in one case. The most predominant manifestation of ocular syphilis was posterior uveitis (54 cases, 67 eyes), followed by optic neuritis (48 cases, 60 eyes), optic atrophy (39 cases, 66 eyes), severe vitritis (vitreous inflammation) (22 cases, 30 eyes), panuveitis (15 cases, 22 eyes), retinal vasculitis (12 cases, 16 eyes), and retinitis (8 cases, 10 eyes). This clearly emphasizes how uveitis can present in ocular syphilis cases beyond the anterior segment, however, the sheer scale of the findings was still surprising.2
Another interesting finding of the study was that in stark contrast to ocular syphilis in developed western countries, which is frequently associated with HIV-positive patients (ranging from 22% to 65%), ocular syphilis was mostly found in HIV-negative patients in China. In fact in the Hangzhou study, only 2 out of 70 ocular syphilis patients undergoing serum tests for antibodies of other pathogens were found to be HIV positive. This lead the researchers to conclude that the prevalence of concurrent ocular syphilis and HIV was similar to that reported in previous investigations from China, indicating that despite a high risk of co-infection in syphilis cases, the concurrent HIV infection rate might be low in China.2
Early Diagnosis is Absolutely Crucial
Another key conclusion of the study emphasized the importance of early testing in achieving the best possible outcomes for patients as late diagnosis is a major cause of permanent visual loss in patients with ocular syphilis. The study found that 69.6% of eyes with active ocular inflammation, compared to 22.7% of eyes with optic atrophy at presentation, achieved best corrected visual acuity (BCVA) better than 20/40 after treatment. Moreover, 80% of eyes with early diagnosis compared to 19.2% of eyes with late diagnosis in the active ocular inflammation group achieved BCVA better than 20/40 after treatment.2
The Hangzhou researchers stated that patients diagnosed with ocular syphilis and uveitis showed a good response to penicillin G treatment and better visual improvement than those with optic atrophy, and that delay in treatment also indicated poor visual prognosis. They found that most ocular syphilis patients with active inflammation responded well to standard penicillin G therapy, no matter what the initial BCVA or ocular disease type. However, cases involving optic atrophy, late diagnosis, permanent disruption, or loss of the outer segment of photoreceptors of macular retina on SD-OCT, showed little visual improvement after therapy.2
So now we know that posterior uveitis is a common manifestation of ocular syphilis and it would be fascinating to follow the Hangzhou researchers in their research to discover other issues related to these diseases. It’s also important to emphasize their concluding remarks, that ocular syphilis may occur without a past medical history or even systemic manifestation of syphilis, which makes early diagnosis so important and yet so challenging.
They recommend routine syphilis testing as a highly recommended routine assay in patients with uveitis, retinitis, optic neuritis, and even optic atrophy. While this may raise some consternation amongst patients, it is a useful and beneficial test for almost anyone, particularly as the rate of HIV co-infection is so low in China.
References
- Koundanya VV, Tripathy K. Syphilis Ocular Manifestations. Stat Pearls. August 22, 2022.
- Sun C, Liu G, Wu R, Liu Z. Demographic, Clinical and Laboratory Characteristics of Ocular Syphilis: 6-Years Case Series Study From an Eye Center in East China. Front Immunol. 2022;13:910337.
