Diffuse Unilateral Subacute Neuroretinitis

date_range May 05, 2026 / person Dr Yasser

Diffuse Unilateral Subacute Neuroretinitis

This Diffuse Unilateral Subacute Neuroretinitis (DUSN) case involves a single, nematode in the right eye, with the fellow left eye remaining completely healthy and unaffected.
The infection was contracted when the child encountered a raccoon nest while helping his father clean a pontoon boat that had been stored for the winter. This environment is a high-risk source for Baylisascaris procyonis, the raccoon roundworm.
Condition Breakdown: DUSN (Right Eye)
  • Cause: Ingestion of infectious B. procyonis eggs from raccoon feces found in the nest. Once inside the body, the larvae migrated to the eye (Ocular Larva Migrans).
  • The Nematode: A  white motile worm  was localized in the subretinal space of the right eye after having caused significant damage.
  • Damage Caused:
      • Early Stage: Recurrent crops of evanescent gray-white outer retinal lesions and mild vitritis caused by the worm’s toxic by-products as it migrated.
      • Late Stage (Wipeout Syndrome): Progressive vision loss due to diffuse retinal pigment epithelium (RPE) degeneration, significant narrowing of retinal vessels, and optic nerve atrophy.

  • Fellow Eye: The left eye remains entirely normal, which is classic for DUSN despite the presence of systemic infection.

Treatment: Laser photocoagulation was used to kill the Nematode.  This can be challenging, since the Nematode is averse to the light used to visualize it. 

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