A surreal digital illustration of a child's eye with a glowing worm, representing the battle against eye worms in DUSN.

Unseen Invaders: The Mystery of Eye Worms and a Child's Fight for Sight

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Lena Kashyap in Health & Wellness November 2025 • 5 min read.

"Delving into the rare condition of Diffuse Unilateral Subacute Neuroretinitis (DUSN) and one girl's battle against elusive eye worms."


Imagine tiny worms, unseen, moving within the delicate structures of your eye. This is the reality for individuals diagnosed with Diffuse Unilateral Subacute Neuroretinitis (DUSN), a rare inflammatory condition affecting the retina. While relatively uncommon, DUSN presents significant challenges in diagnosis and treatment, often leaving patients with long-term visual impairment. Let's uncover one case where the mystery of eye worms led a young girl and her doctors on a diagnostic and therapeutic journey.

Diffuse Unilateral Subacute Neuroretinitis (DUSN) is a rare cause of posterior uveitis, an inflammation of the uvea, the middle layer of the eye. What makes DUSN particularly challenging is that, until later stages, it typically manifests in only one eye, primarily affecting children and young adults. Even more rare are cases where multiple worms are present, or the condition does not respond to conventional treatments. This article will share the story of an 8-year-old girl who battled DUSN.

In a medical journal, Curragh et al. (2018) details the intricacies of a specific DUSN case, highlighting the complexities encountered when treating this condition. The case emphasizes the difficulties in diagnosis, the potential for multiple worms contributing to the disease, and the limited success of conventional treatments. It is important to understand that DUSN is not just a single disease with a single solution. It is a complex interplay of infection, inflammation, and the body's immune response.

The Case of the Young Girl with Mysterious Headaches

A surreal digital illustration of a child's eye with a glowing worm, representing the battle against eye worms in DUSN.

In August 2015, an 8-year-old girl was brought to the Royal Belfast Hospital for Sick Children due to persistent headaches that had been increasing in both intensity and frequency for two months. Sometimes, her headaches were associated with redness and watering of her left eye. The girl’s doctor had noted some abnormalities on her left fundus. What was odd was the fact that she had no vision loss or any other symptoms. Her medical history included some additional factors. She had nosebleeds, but she never had foreign travel besides a vacation to Spain. Furthermore, she also had a pet dog. The doctors were puzzled.

Upon examination, the girl's visual acuity was 6/6 in the right eye, but significantly reduced to 6/30 in the left eye. Her left eye fundus, the back portion of the interior eyeball, revealed a unilateral chorioretinitis. This condition involves inflammation of the choroid (the vascular layer of the eye) and the retina. She was admitted with findings of left posterior uveitis and mild vitritis for further investigation. The doctors suspected infectious chorioretinitis such as toxoplasma, toxocara, tuberculosis, syphilis, and inflammatory chorioretinitis.

The doctors considered several possibilities, including:
  • Infections: Toxoplasmosis, toxocariasis, tuberculosis, syphilis, and Lyme disease (borreliosis)
  • Inflammatory conditions: Sarcoidosis and other white dot syndromes
  • Other infiltrative causes
  • Post-streptococcal syndrome
Extensive laboratory testing was performed. Over the next four months, and with no treatment, her vision improved to 6/12 in the left eye. Her fundus appearance improved, but she had a focal circular area of chorioretinitis along the superotemporal arcade. A month later, the chorioretinitis had faded, but a new active area of chorioretinitis was noted, where an elongated, glistening nematode was identified with an estimated size of 1500 μm.

Hope for Future Treatments

This case underscores the challenges of DUSN, particularly in cases unresponsive to standard treatments. Further research is needed to understand the pathogenesis of DUSN and to develop more effective treatments. Early diagnosis and prompt intervention are crucial to minimizing visual loss and improving outcomes for patients with DUSN. While rare, DUSN serves as a reminder of the complex interplay between parasitic infections and the human body. Awareness, vigilance, and continued research are essential to combating this elusive and sight-threatening condition.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

1

What is Diffuse Unilateral Subacute Neuroretinitis (DUSN), and what makes it particularly challenging to diagnose and treat?

Diffuse Unilateral Subacute Neuroretinitis (DUSN) is a rare inflammatory condition affecting the retina, leading to posterior uveitis, which is the inflammation of the uvea. It primarily affects one eye and is often seen in children and young adults. Diagnosis is challenging, and the presence of multiple worms or resistance to conventional treatments further complicates the condition, as highlighted in the case study by Curragh et al. (2018).

2

What are the initial symptoms of Diffuse Unilateral Subacute Neuroretinitis (DUSN) that might prompt a medical investigation?

The initial symptoms of Diffuse Unilateral Subacute Neuroretinitis (DUSN) can be subtle and may include headaches, eye redness, and watering, as observed in the 8-year-old girl's case. Unilateral chorioretinitis, which is the inflammation of the choroid and retina in one eye, is also a key indicator. Vision loss may not be immediately apparent, making early detection challenging.

3

What other conditions do doctors consider when diagnosing Diffuse Unilateral Subacute Neuroretinitis (DUSN), and what tests are performed?

In diagnosing Diffuse Unilateral Subacute Neuroretinitis (DUSN), doctors consider various possibilities, including infectious causes such as toxoplasmosis, toxocariasis, tuberculosis, syphilis, and Lyme disease, as well as inflammatory conditions like sarcoidosis. The diagnostic process involves extensive laboratory testing to rule out these potential causes. In the case of the young girl, the doctors had to consider a broad range of infectious and inflammatory possibilities before identifying the nematode.

4

What is the significance of identifying a nematode in the eye when diagnosing Diffuse Unilateral Subacute Neuroretinitis (DUSN)?

The presence of a nematode in the eye, as observed in the case study, indicates an active parasitic infection causing Diffuse Unilateral Subacute Neuroretinitis (DUSN). Identifying and targeting these elusive eye worms is crucial for treatment. The case emphasized that the nematode was 1500 μm in length. The discovery of the worm is key to understanding the etiology and guiding appropriate interventions, though challenges remain if the condition is unresponsive to standard treatments.

5

What does the case study reveal about the challenges in treating Diffuse Unilateral Subacute Neuroretinitis (DUSN), and what are the implications for future research and treatment?

The case study underscores the challenges in treating Diffuse Unilateral Subacute Neuroretinitis (DUSN), particularly when it doesn't respond to conventional treatments. It highlights the need for further research to understand the pathogenesis of DUSN and develop more effective therapies. Early diagnosis and prompt intervention are critical to minimize visual loss and improve outcomes. The case serves as a reminder of the complex relationship between parasitic infections and the human body.

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