Unilateral Photopsia: An Unusual Case of Syphilitic Endophthalmitis.

Syphilitic endophthalmitis represents a rare ocular manifestation that can occur in both immunocompetent and immunocompromised patients. It is often misdiagnosed due to its resemblance to many other infectious, inflammatory, malignant, and rheumatologic conditions. This report describes the case of a 66-year-old male patient who presented with visualizing bright lights in the left eye associated with a significant decline in visual acuity. A series of investigations was done, including a temporal artery biopsy with unremarkable findings. Furthermore, vitreous aspiration was performed with Gram stain revealing trace gram-positive cocci with negative culture results. Intra-vitreal vancomycin and ceftazidime were given with no symptomatic improvements. On the other hand, the serum rapid plasma reagin (RPR) titer was 1:128 with positive syphilis serologies. The patient was started on penicillin-G 4 million units intravenously every four hours for two weeks, followed by benzyl-penicillin 2.4 million units intramuscularly weekly for three weeks. Significant improvement in visual acuity was noted after completion of antibiotic therapy, with routine retinal screening demonstrating resolution of hypopyon. This case illustrates the importance of screening for syphilis in patients with unexplained changes in visual acuity, as prompt identification of syphilis and initiation of treatment are associated with favorable outcomes.