History of Present Illness
A 56-year-old man presents with a paracentral blind spot and floaters right eye (OD), but no ocular pain, for about 4 weeks. He first noticed the blind spot while hunting in Michigan and closing his left eye (OS). He has been in excellent health and enjoys hunting, fishing, and swimming in the outdoors. He does not recall being bitten by an insect or tick this fall while hunting deer.
| OD | OS | |
|---|---|---|
| Visual acuity | 20/60 | 20/20 |
| Intraocular pressure (IOP) (mm Hg) | 10 | 9 |
| Sclera/conjunctiva | Clear. No injection | Clear. No injection |
| Cornea | Clear | Clear |
| Anterior chamber (AC) | No cell or flare | No cell or flare |
| Iris | No relative afferent pupillary defect (RAPD) | Normal |
| Lens | Clear | Clear |
| Vitreous cavity | 2+ vitritis | Clear |
| Retina/optic nerve | White worm within the macula ( Fig. 44.1 ) | Normal |
Questions to Ask
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Have you been in the woods within the past 3 months hunting or swimming in rivers?
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Do you eat the animals that you have hunted?
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Have you eaten steak tartare or other raw meat in the past?
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Do you have unprotected sex with women or men?
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Have you traveled to the tropics within the past 6 months?
He has been hunting in Michigan for the past 3 months during the fall deer season and was successful in bringing down a white-tailed deer as part of a deer culling program in Ann Arbor. He does not usually eat game, but he and a few friends had a cookout at the end of the day. He has not had unprotected sex with either gender and has never been to the tropics.
Assessment
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Posterior uveitis with chorioretinitis, OD
Differential Diagnosis
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Infectious chorioretinitis (nematode, parasite)
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Unlikely: syphilis, sarcoidosis
Working Diagnosis
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Diffuse unilateral subacute neuroretinitis (DUSN), OD
Testing
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Laboratory testing: normal complete blood count (CBC) with mild eosinophilia
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Visual field (VF): paracentral blind spot, OD
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Fluorescein angiography (FA): diffuse degeneration of retinal pigment epithelium (RPE) and peripapillary capillary dye leakage, OD
Management
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Laser photocoagulation was performed on the live worm, who initially moved but was subsequently surrounded by laser spots and directly photocoagulated.
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Return appointment in 1 week.
Follow-up
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At the 1-week appointment, clinical examination OD was unchanged but there was no increase in intraocular inflammation.
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At 1 month, VA improved to 20/40 and mild vitritis resolved.
Key Points
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Early stage: mild optic nerve edema, mild vitritis, optic disc edema, and clustered yellow-gray-white lesions ( Fig. 44.2 ). Late stage: optic nerve atrophy, retinal arteriolar narrowing, increased internal limiting membrane reflex, subretinal tunnels, diffuse RPE degeneration, and afferent pupillary defect ( Fig. 44.3 ).
