Acute cat scratch neuroretinitis, formally bilateral disc edema and neuroretinitis secondary to Bartonella infection, can be an unexpected side effect of bringing a stray cat into one’s home, as a 52-year-old patient at the John D. Dingell Veterans Affairs (VA) Medical Center in Detroit learned.
The patient presented with vision loss in his left eye and blurry vision on his periphery. He had spent the prior 4 days noticing a black spot over his vision.
Upon evaluation, the optometry team noted an afferent pupillary defect (APD). Optic nerve exams showed a grade 2 disc edema in the right eye and a grade 4 edema in the left; and his cup-to-disc ratio was indeterminable due to the swelling. He also had cotton wool spots at the posterior pole. With optical coherence tomography (OCT), a serous macular detachment was discovered in his left eye, and swollen nerves in both eyes. After consulting with the VA’s neurology team, a series of lab tests were conducted, revealing Bartonella infection. Unlike most Bartonella cases, this patient had a bilateral cat scratch neuroretinitis presentation.
Neuroretinitis is decreased optic nerve head connectivity due to inflammation. “Most patients (88%) will have a central visual field defect, similar to what my patient came in with,” presenting clinician Hady Srour, OD, explained. “About two-thirds will have an APD.” Presenting acuity for neuroretinitis cases can be as poor as 20/200 in more than half of these patients, although final acuity usually (93% of the time) resolves to 20/40 or better.
The patient was treated with IV methylprednisolone, oral doxycycline 100 mg and rifampin 300 mg, both twice daily. Later he was switched to prednisone 80 mg, tapered to 60 mg in 2 weeks, and then to 10 mg. But, after the first week, he appeared for a follow up appointment and was found to have vision improvement (20/400 OS without correction). At a second follow-up 5 days later, vision in the left eye had improved to 20/200 and the disc edema had begun to resolve.
Research referenced in the presentation shows that patients without any APD can still present with count finger visual acuity, suggesting that visual impairment in neuroretinitis is due to macular pathology, not optic nerve dysfunction.
Systemically, patients with acute cat scratch neuroretinitis can also report fever, headache, fatigue, lymph node swelling, and even skin pustules at the scratch site.
“In cases of neuroretinitis caused by cat scratch disease seen acutely, treatment with a broad-spectrum antibiotic is reasonable while serologic tests are pending,” Dr Srour said. “Especially in cases with findings suggestive of an infectious cause (exposure to cats.)”
Srour H, Gold A. Scratch that, cat edition. Poster presented at: American Optometric Association 2023 ePosters Virtual Event; June 13-14, 2023; Washington, DC. Poster 787.