A 46-year-old Brazilian woman came into casualty with a one-day history of red eye, light sensitivity and floaters. Her VA is 6/36. You diagnose acute anterior uveitis (AAU).
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1. What would you see in the anterior chamber in order to diagnose this?
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Correct answer: Just as there is a blood–brain barrier, there are two such impermeable areas in the eye:
- The blood–retinal barrier
- The blood–ocular barrier.
When there is a marked inflammatory response, such as uveitis, these vessels become leaky. Hence, one can see cells (white blood cells) and flare (proteins) in the aqueous of the anterior chamber.
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2. Broadly categorise the causes of AAU.
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Correct answer:
Broadly categorise AAU into infectious and non-infectious. It can be seen that ophthalmologists need to have a sound medical knowledge in order to diagnose these systemic conditions:
- Non-infectious
- Idiopathic (most common)
- HLA-B27 (inflammatory bowel disease and sero-negative arthritis)
- Sarcoid
- Bechet’s disease
- Juvenile idiopathic arthritis
- Traumatic
- Hypermature cataract
- Fuch’s heterochromatic cyclitis.
- Infectious
- Herpes simplex virus
- Herpes zoster virus
- Tuberculosis
- Syphilis
- Lyme disease
- Delayed postoperative endophthalmitis
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3. What other signs would you look for in the eye to aid your underlying diagnosis?
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Correct answer: In order to determine the underlying cause of the AAU, look for the following signs:
- Cornea
- Mutton fat keratitic precipitates are white blood cells on the endothelium. They are seen in any cause of granulomatous uveitis:
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Check corneal sensation:
- Reduced in herpetic disease.
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Iris
- Nodules are seen in granulomatous disease:
- Pupillary margin = Koeppe nodules
- Ciliary zone = Busacca nodules.
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Transillumination defect:
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Heterochromia:
- Fuch’s heterochromatic cyclitis.
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Anterior chamber
The medical retina fellow asks you to dilate the patient and have a closer look at the posterior segment. You see active vitritis and a fluffy lesion proximal to the macula.
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4. What is the most likely diagnosis?
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Correct answer: This is a posterior uveitis, and from the history there is no indication that it has an immunological cause. The only clue is the patient’s country of origin: in Brazil, a higher prevalence, a greater severity and more virulent strains of the protozoan Toxoplasma gondii are found.
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5. Given the location of the lesion and her VA, would you treat?
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Correct answer: One can withhold treatment if the patient is immunocompetent, the active lesion is in the periphery and the VA is not overly reduced.
In this instance, treatment should be administered, and the following considered:
- Pyrimethamine (with folic acid)
- Sulfadiazine
- Clindamycin
- Prednisolone (if immunocompetent).
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6. If this was a recurrent and resistant immune-related (non-infectious) posterior uveitis, is there anything you can administer to control the inflammatory response?
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Correct answer: Recently, the HURON group showed that a sustained-release implant into the vitreous has a role in this particular scenario. The primary outcome was the degree of vitreous haze after 8 weeks in patients with dexamethasone implant versus sham; the percentage of patients with a vitreous haze score of zero at 8 weeks was 47% versus 12%, respectively.
