Toxoplasmosis in the outer retina

Objective: To present a case of ocular toxoplasmosis. Materials and methods: A sixteen-year-old female patient presented to our clinic with complaints regarding decreased vision in her right eye (BCVA 0.5), starting five days before the exam. Her anamnestic data revealed a previous history of ocular toxoplasmosis in her left eye. OCT scans of the inner retina identified a huge cystic space, located posterior to the inner line, off the outer plexiform layer, with a small amount of hyperreflective foci. Other features of OCT included membranous-like structures on inner borders and elongation and splitting of the inner segment/outer segment junction. In later stages, beginning signs of retinitis and scaring could be observed. Results: The patient was treated with sulfamethoxazole/trimethoprim and prednisolone. After two weeks, total regression occurred and visual acuity and OCT remained stable for 6 months (BCVA 1.0). Discussion: Ocular toxoplasmosis can cause significant vision loss due to retinitis and scarring. Following treatment with sulfamethoxazole/trimethoprim and prednisolone, the patient's condition improved significantly and her visual acuity remained stable. Conclusion: On clinical examination and using OCT, rare morphological cystoid spaces (CS) can be identified as huge outer retina cysts (HORC), which are pathognomonic for posterior uveitis. Abbreviations: HORC = huge outer retinal cyst, OCT = optical coherence tomography, BCVA = best corrected visual acuity, CS = cyst space, OPL = outer plexiform layer, HRF = hyper reflective foci, RPE = retinal pigment epithelium, IS = inner segment, OS = outer segment, ERM = epiretinal membrane, PORT = punctate outer retinal toxoplasmosis, ELM = external limiting membrane.