# Characteristic Optical Coherence Tomography and Magnetic Resonance Imaging Findings in a Case of Seronegative Neuroretinitis

## TL;DR

A 42-year-old man with a tick bite and vision loss was diagnosed with neuroretinitis using MRI and OCT, despite negative tests for Lyme disease.

## Contribution

This case highlights characteristic MRI and OCT findings in seronegative neuroretinitis linked to a tick bite.

## Key findings

- MRI showed increased thickening and enhancement in the left optic disc.
- OCT revealed optic nerve edema, intraretinal fluid, and subretinal fluid distortion.

## Abstract

Neuroretinitis is a rare ophthalmologic disorder that presents with painless loss of vision. In this report, we describe the magnetic resonance imaging (MRI) findings in a case of seronegative, idiopathic neuroretinitis, which occurred in the setting of a recent tick bite. A 42-year-old man with no past medical history of eye complaints presented to Saint Louis University Emergency Department with painless loss of visual acuity in his left eye worsening over the span of one week. The patient denied additional ocular symptoms and any symptoms of recent infection such as headache, fever, cough, sore throat, chest pain, joint pain, nausea, and vomiting. Relevant recent history was limited to a report of a tick bite while traveling in Illinois that was followed by a self-resolving “red ring” rash. However, infectious workup, including tests for Lyme disease antibody, was negative. An MRI of the brain and orbits with and without contrast was performed, demonstrating increased thickening and enhancement in the left optic disc. Ocular coherence tomography (OCT) demonstrated optic nerve edema with intraretinal fluid with scattered exudates extending to fovea, along with distortion of contour of subretinal fluid. These imaging findings, in conjunction with patient history and fundoscopic examination, supported a diagnosis of neuroretinitis with no identified etiology.