A 35-year-old man is brought to the emergency department due to deteriorating vision for the past week. He initially experienced eye pain and mild redness of both eyes, followed by visual blurring and photophobia over the previous few days. The patient has a history of HIV diagnosed 10 years ago and has not been taking his antiretroviral medications. Temperature is 37.2 C (99 F), blood pressure is 110/81 mm Hg, and pulse is 82/min. Profuse clear drainage and crusting of the eyes is noted bilaterally. Slit-lamp examination reveals marked linear branching keratitis. Funduscopy shows a normal-appearing retina and optic nerve. Oral examination reveals numerous white plaques over the buccal mucosa, palate, and tongue. Which of the following organisms is the most likely cause of this patient's ocular findings?
Infectious keratitis | ||
Pathogen | Risk factors | Clinical features* |
Bacteria (eg, Staphylococcus aureus, Pseudomonas) |
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Herpes simplex virus |
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Fungi (eg, Candida) |
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*Eye pain/redness, blurred vision & photophobia are features of all infectious keratitis. | ||
This patient has infectious keratitis, or inflammation of the cornea. Corneal infection leads to eye pain/redness, blurred vision, and photophobia (as seen in this patient), and can be caused by bacteria, viruses, or fungi.
Because untreated disease can lead to permanent visual impairment and blindness, prompt antimicrobial therapy is warranted. Ophthalmologic findings can often differentiate various pathogens to guide management decisions.
Dendritic ulcerations: Branched linear lesions are characteristic of herpes simplex virus (HSV) keratitis, the most likely diagnosis in this case; vesicles may also be present. Immunocompromised patients (eg, advanced HIV infection) are at increased risk and are more likely to have bilateral involvement, as in this patient. Clear, watery eye drainage is typical, and recurrent episodes are common. Management is topical or oral antiviral therapy (eg, acyclovir, valacyclovir).
Central round infiltrate: This lesion is typically seen in bacterial keratitis (eg, Pseudomonas aeruginosa, Staphylococcus aureus) (Choices D and E). Patients who use contact lenses improperly (eg, extended wear, infrequent cleaning) are at highest risk, and symptoms usually include mucopurulent discharge, not seen here. Management is topical antibiotic therapy.
Multiple ulcers with feathery margins: These findings are typical of fungal (eg, Candida) keratitis (Choice A). This diagnosis is rare and typically also presents in immunocompromised patients but usually after corneal trauma (not seen here), particularly when involving contaminated soil (eg, thorn, twig). In addition, disease progression is usually more gradual compared to bacterial and viral keratitis. Treatment is with topical or oral antifungals. This patient's mouth findings are consistent with mucocutaneous candidiasis (eg, thrush) that is often seen in immunocompromised patients but is unrelated to his ocular findings.
(Choice B) Cytomegalovirus retinitis is the most common serious ocular complication in patients with HIV and causes progressive loss of vision. However, it is typically painless, and funduscopy shows fluffy or granular retinal lesions near the vasculature as well as retinal hemorrhages. This patient's pain, normal funduscopic examination, and branching ulcerations are inconsistent with this diagnosis.
Educational objective:
Infectious keratitis causes eye pain/redness, photophobia, and blurred vision. Slit-lamp examination revealing branching dendritic corneal ulcerations is diagnostic of herpes simplex virus keratitis; patients with HIV are at increased risk.