Ocular syphilis presents with different and nonspecific signs and symptoms. For the eye, iridocyclitis, intermediate and posterior uveitis, scleritis, keratitis, chorioretinitis, retinal vasculitis and neuritis have been reported in cases of ocular syphilis. In our case, no obvious signs of inflammation were observed in the anterior segment or intermediate optic media. No abnormal color tone or edema was detected in the optic nerve head, and leakage from the optic disc except from the neovascular tissue, was not significant in the FA images. In addition, there were no obvious systemic signs of syphilis. This case was characterized by the bilateral optic disc neovascularization, retinal ischemia, and extensive retinal pigment epithelium atrophy of both eyes. These clinical findings indicated that this was a case of atypical ocular syphilis. The presence of nonperfused areas in the peripheral retina in FA suggested that vasculitis or vascular occlusion occurred not only around the optic disc where the neovascular tissue was present but also throughout the retina which resulted in the ischemic changes.
A case of ocular syphilis complicated by retinal vasculitis, proliferative retinopathy, and vitreous hemorrhages was reported by Kobayashi et al. Similar to our case were the severe retinal ischemic changes and lack of systemic findings. However, their case differed from our case by the presence of obstructive retinal vasculitis. In addition, the visual acuity in our case was good throughout the course of the disease. Also, our case had window defects throughout the retina which was not reported for their cases. The speed of progression of the two eyes was different in their case which was not true in our case. The findings indicated the necessity to perform appropriate treatments promptly to prevent vitreous hemorrhage.
There are other cases of ocular syphilis that required vitreoretinal surgery. In one case, vitreous hemorrhage developed from occlusive retinal vasculitis. Other cases developed rhegmatogenous and tractional retinal detachment that progressed to retinal necrosis. Haug et al reported that four of 11 acute syphilitic panuveitis eyes (36.4%) had a redetachment of the retina. These reports suggest that it is important to prevent progression to vitreous hemorrhage and proliferative changes. Therefore, a rapid suppression of the ischemic changes using IVB prior to photocoagulation therapy may be effective in cases with severe neovascularizations.
It is difficult to detect inflammation by OCTA unlike FA, however OCTA can detect nonperfused and neovascular areas. OCTA is occasionally better in detecting vascular abnormalities, retinal capillary changes, and neovascular formation than FA. Abucham-Neto et al studied vasculitis cases with syphilis and reported that early peripapillary neovascular proliferation, telangiectasia, and neovascularization obscured by retinal hemorrhage were detected better by OCTA than by FA. Residuals of neovascularization around the optic disc after IVB were clearly confirmed by OCTA in our case. Therefore, OCTA can be useful complementary diagnostic tool in cases of uveitis especially in cases with ischemic changes and neovascularization as our case. Because there are few reports of OCTA regarding syphilis, further studies about OCTA of ocular syphilis with larger sample sizes are needed.
Electroretinographic studies have not been performed on cases of ocular syphilis that underwent PRP with severe ischemia such as in our case. However, there are several reports of ERG evaluations on comparatively mild ocular syphilis cases. Many of the reports showed that treatment for syphilis improved the ERG waveforms. No obvious ERG improvements were observed in our case unlike the earlier reports. It has been reported that PRP treatments reduced the ERG amplitudes significantly. Therefore, the ERG amplitudes decrease due to PRP treatment in addition to the prolongation of retinal disfunction due to ocular syphilis may have occurred in our case. The ERG evaluations of cases treated with PRP should be performed carefully.
A limitation of this case report is that magnetic resonance imaging of the brain and spinal cord and lumbar puncture were not performed to further evaluate the evidence of neurosyphilis.
In summary, we have presented our findings in an atypical case of ocular syphilis with optic disc neovascularization. The neovascularization on the optic disc was suppressed by IVB, however its effect was transient and PRP treatment was required. In addition to FA, OCT angiography was useful for evaluating the optic disc neovascular activity. ERG evaluations were also important because ERG disorders may be prolonged as in this case even after the activity of ocular syphilis is suppressed by systemic and focal treatments.