Case Study
A 27-year-old male presented with sudden-onset blurred vision and a central scotoma in his right eye.
He reported a recent history of low-grade fever, malaise, and lymphadenopathy following a scratch from his pet cat. Best-corrected visual acuity (BCVA) was 20/80 in the right eye and 20/20 in the left eye.
Fundus examination revealed optic disc swelling with a macular star (classic stellate maculopathy). Optical coherence tomography (OCT) demonstrated subretinal fluid and exudates in the macula, and fluorescein angiography (FA) confirmed disc leakage.
Serology for Bartonella henselae was positive, confirming the diagnosis of Bartonella henselae neuroretinitis.
The patient was treated with doxycycline and rifampin, leading to the gradual resolution of symptoms over three months.
Disease Entity
Bartonella henselae neuroretinitis is an infectious, inflammatory optic neuropathy characterized by unilateral optic disc swelling and macular exudates forming a star pattern.
It is one of the most common causes of infectious neuroretinitis and is strongly associated with cat scratch disease (CSD).
Pathophysiology
Bartonella henselae is a gram-negative, intracellular bacterium transmitted through cat scratches, bites, or flea vectors.
The pathogen invades the vascular endothelium and immune cells, triggering an inflammatory response that affects the optic nerve and retina.
The hallmark findings—optic disc swelling and macular star—occur due to:
- Optic nerve inflammation leading to disc edema.
- Leakage of plasma lipoproteins into the Henle fiber layer, forming a macular star.
Epidemiology
- Age group: Primarily affects children and young adults.
- Transmission: Occurs via cat scratches, bites, or flea vectors.
- Prevalence: Common in areas with a high domestic cat population.
Clinical Features
Symptoms
- Sudden, painless vision loss (mild to moderate).
- Central or paracentral scotoma.
- Photopsia (flashes of light) in some cases.
- Mild systemic symptoms (low-grade fever, fatigue, lymphadenopathy).
Fundoscopic Findings
- Unilateral optic disc edema (hyperemic, swollen disc).
- Macular star (exudates forming a stellate pattern in the Henle fiber layer).
- Mild retinal vascular changes.
- Absence of vitritis (distinguishing it from infectious posterior uveitis).
Imaging Findings
- Optical Coherence Tomography (OCT):
- Thickened optic nerve head.
- Intraretinal hyperreflective deposits at the macula.
- Fluorescein Angiography (FA):
- Optic disc leakage without significant retinal vasculitis.
- Fundus Autofluorescence (FAF):
- Hyperautofluorescence at sites of exudation.
Differential Diagnosis
- Idiopathic Neuroretinitis: Lacks systemic Bartonella exposure history.
- Leber’s Hereditary Optic Neuropathy (LHON): Typically bilateral and progressive.
- Viral or Syphilitic Optic Neuritis: Often associated with vitritis or vasculitis.
- Hypertensive Retinopathy: Features flame hemorrhages and cotton wool spots.
Diagnosis
- Clinical history (cat exposure, systemic symptoms).
- Serologic testing for Bartonella henselae IgM/IgG (enzyme-linked immunosorbent assay [ELISA] or polymerase chain reaction [PCR]).
- Ocular imaging (OCT, FA, FAF) to confirm neuroretinitis findings.
Management
Antimicrobial Therapy
- Doxycycline (100 mg BID) + Rifampin (300 mg BID) for 4-6 weeks.
- Alternative: Azithromycin, especially in children or pregnant patients.
Anti-inflammatory Treatment
- Oral corticosteroids (Prednisone 40-60 mg/day, tapered) if severe optic disc edema persists.
- Avoid early steroid use without antibiotics to prevent worsening infection.
Supportive Care
- Regular follow-up with OCT and visual field testing.
- Amsler grid home monitoring for early detection of progression.
Prognosis
- Generally favorable: Most patients recover vision within 2-6 months.
- Residual visual impairment: Some cases develop persistent optic disc pallor or mild scotomas.
Conclusion
Bartonella henselae neuroretinitis is an infectious optic neuropathy presenting with sudden vision loss, optic disc swelling, and macular star formation. Diagnosis is based on clinical history, serologic testing, and imaging. Early antibiotic therapy leads to excellent recovery, making timely recognition essential.
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References
- Solley WA, Martin DF, Newman NJ, et al. “Cat scratch disease: posterior segment manifestations.” Ophthalmology. 1999;106(8):1546-1553.
- Reed JB, Scales DK, Wong MT, et al. “Neuroretinitis: A review of the literature and new observations.” Surv Ophthalmol. 1998;43(2):155-180.
- Mazur-Melewska K, Mania A, Kemnitz P, et al. “Cat scratch disease: A wide spectrum of ocular manifestations.” Eur J Pediatr. 2015;174(9):1193-1200.
- Ormerod LD, Dailey JP. “Ocular manifestations of cat-scratch disease.” Curr Opin Ophthalmol. 1999;10(3):209-216.
