Neuroretinitis -- To Treat or Not to Treat
BY LEO SEMES, OD, FAAO
A 28-year-old dental student presented to my office complaining of a two-day history of a floater in his right eye. He had no other visual or ocular complaints. His medical history was non-contributory with standard questioning. Visual acuity was correctable to 20/20 in each eye with minimal refractive error.
Figure 1 shows the slit lamp biomicroscopy view of the involved right eye. It contains two items of note: the granuloma that we believe was responsible for the floater and the slight elevation of the optic disc superior nasally. Look carefully for this slightly blurred disc margin.
Upon further questioning, the patient offered that he had a new kitten in the household that had scratched the back of his hand. He showed that it was still healing about two weeks following the incident.
Figure 1. Right eye on presentation with granuloma (superior temporal to the optic disc) and subtle optic disc
A Case of "Cat-Scratch Fever"
The components of this case add up to the diagnosis of neuroretinitis, in all probability secondary to Bartonella henselae bacterial infection resulting from the kitten's scratch. This case didn't involve the macula.
We offered the patient treatment with Bactrim DS, a combination of 800mg sulfmethoxazole and 160mg trimethoprim. It's contraindicated for sulfa-sensitive patients because of the sulfmethoxazole. No contraindication to trimethoprim exists among sulfa-allergic patients. Our patient took this oral medication for four weeks, and the retinal picture resolved.
A few items of significance surround this case. First, not all agree that we should offer treatment for this diagnosis. In some instances, the condition is self-limiting. We offered the treatment option to our patient to prevent macular involvement because he has an important binocular visual demand as a result of his area of study.
Second, the involvement of the optic nerve and retina qualify the diagnosis of neuroretinitis and make a good clinical descriptor. When patients are asymptomatic, the infection may naturally resolve or cause complications such as macular star with variable reduction of visual acuity. When accompanied by optic disc edema, this complication sometimes goes by the acronym ODEMS (optic disc edema with macular star).
Other potential sequelae include occlusion/obstruction of the central artery or vein. These ischemic situations may result in neovascular glaucoma. Clinicians should remain alert to potential sight-threatening consequences.
Getting to the Source
Bartonellosis, because of its associated feline vectors, is often called "cat-scratch disease." This is somewhat of a misnomer in that kittens -- not cats -- are generally the vector. But somehow, I just don't see how Ted Nugent could have done anything with "Kitten-Scratch Fever."
Dr. Semes is an associate professor at the University of Alabama at Birmingham School of Optometry.