A 43-year-old woman presented with impaired vision in her left eye for the previous 2 weeks. She had a non-traumatic unilateral red eye, chemosis, and untreated hypertension. At the initial visit, the respective right and left corrected visual acuities were 20/16 and 20/2000, and the bilateral intraocular pressure was 20 mm Hg. The chemosis was accompanied by serous discharge, keratic precipitates, partial synechia of the iris and cells (2+) in the anterior chamber (Figure 1 (Fig. 1), Figure 2 (Fig. 2)), and vitreous of the left eye. A fundus examination of the left eye showed optic disc swelling, a focal retinitis lesion at the temporal margin of the optic disc, macular exudates in a star pattern, a flame-like retinal haemorrhage, and a serous macular detachment (Figure 3 (Fig. 3), Figure 4 (Fig. 4)). Fluorescein angiography showed leakage from the optic disc of the left eye (Figure 5 (Fig. 5)). No signs of inflammation were apparent in the right eye. The patient reported that her pet cat had scratched her forehead 3 weeks before she presented for examination. She did not have a fever, any detectable skin lesions, or lymphadenopathy. An infectious disease specialist performed a systemic examination and found no evidence of systemic CSD or any other infectious disease.
Since conjunctivitis and iridocyclitis were present in addition to the aforementioned fundus findings, extensive investigations for uveitis were conducted that included measurement of the total blood count and erythrocyte sedimentation rate (ESR) as well as tests for autoantibodies, syphilis, viruses, and toxoplasma antibody. Except for a slightly elevated ESR rate (26 mm/hour), the results were unremarkable. Angiotensin-converting enzyme, soluble interleukin-2 receptor, and chest x-ray parameters were all within the normal limits. A blood sample was sent to a pathology laboratory for serology testing for B. henselae antibody.
Since optic disc edema is associated with a macular star, it is important to exclude other causes such as malignant hypertension, sarcoidosis, toxoplasmosis, tuberculosis, and spirochetal disease. The systemic blood pressure was 160/91 mm Hg, and all blood test results were within the normal limits, with the exception of the slightly elevated ESR. QuantiFERON TB (Qiagen, Germantown, MD, USA) was negative. Serology testing for B. henselae antibodies was the only positive test result (IgM titre 1:16, IgG titre 1:256). Serology tests for cytomegalovirus, toxoplasma, and human immunodeficiency virus were negative.
Given the clinical ocular findings and the reported cat scratch, CSD was suspected even without systemic illness. Oral doxycycline 200 mg/day and prednisolone 20 mg/day with tapering were prescribed. Topical corticosteroid and mydriatic treatments were administered for the anterior chamber inflammation.
After the initiation of treatment, the optic disc edema, focal retinal infiltrates, retinal haemorrhage, serous retinal detachment, and macular exudates gradually decreased (Figure 6 (Fig. 6)). The cells in the anterior chamber and vitreous resolved over the treatment course. However, it is noteworthy that the focal retinitis persisted and doxycycline was prescribed for 3 months. Six months after the start of treatment, macular atrophy developed and the visual acuity remained 20/40.