What are the effects of drug use on the anterior chamber of the eye, potentially leading to endophthalmitis, in an adult patient with a history of substance abuse?

Repeated Injection Drug Use in the Antecubital Fossa: Ocular Complications

If you have a patient with a history of intravenous drug use presenting with eye symptoms, you must urgently evaluate for endogenous endophthalmitis—a sight-threatening emergency that requires immediate ophthalmologic consultation and intravitreal antibiotic injection. 1, 2

Understanding the Connection Between IV Drug Use and Eye Infection

Intravenous drug abuse is a well-established risk factor for endogenous endophthalmitis, accounting for a significant proportion of cases in multiple case series. 3 When bacteria or fungi enter the bloodstream through contaminated injection sites (like repeated use of the antecubital fossa), they can seed the eye via hematogenous spread, crossing the blood-eye barrier to infect the vitreous and aqueous humors. 1, 2

Key pathogens in IV drug users include:

• Staphylococcus aureus and streptococci (most common bacterial causes associated with endocarditis) 2
• Candida species, particularly Candida albicans in hospitalized patients with indwelling catheters 1, 2
• Fungal endophthalmitis is also associated with immunosuppression and prolonged hospitalization 1

Clinical Presentation to Recognize Immediately

The infected eye presents with:

• Decreased vision (present in nearly all cases) 4
• Eye pain (variable, but common) 5, 4
• Hypopyon (layered white blood cells in the anterior chamber) 4
• Intraocular inflammation visible on examination 4
• Conjunctival injection and chemosis may be present 6

Critical distinction: The patient may present without fever or systemic symptoms because bacteremia/fungemia can be transient, and the infected eye does not serve as a source of systemic infection. 2, 5 Do not be falsely reassured by absence of systemic signs.

Immediate Management Algorithm

Step 1: Emergency Ophthalmology Consultation

Any IV drug user with eye pain, vision changes, or visible anterior chamber abnormalities requires immediate ophthalmologic evaluation—this is a medical emergency. 5, 4 Delay in treatment results in permanent vision loss. 5

Step 2: Diagnostic Approach

• Obtain vitreous and/or aqueous cultures (performed by ophthalmologist) 4
• Blood cultures should be drawn, though bacteremia may be transient 4
• Culture positivity rates are approximately 64% 3

Step 3: Treatment Priorities

The most important treatment component is intravitreal injection of antibiotics—this takes precedence over all other interventions. 2, 4

For bacterial endophthalmitis:

• Intravitreal antibiotics are mandatory 2, 4
• Vitrectomy is indicated in severe cases and is advocated for bacterial-proven cases (57% vitrectomy rate in documented bacterial cases) 3
• Systemic antibiotics are indicated for endogenous endophthalmitis 2, 5

For fungal endophthalmitis (Candida):

• Systemic antifungal therapy with amphotericin B, fluconazole, or voriconazole 7
• Sight-threatening lesions may require intravitreal antifungal injection or vitrectomy 1
• Decisions should be made jointly by ophthalmologist and infectious diseases physician 1, 7

Step 4: Repeated Interventions if Needed

Repeated intravitreal injections may be necessary if there is no response to initial therapy. 2

Prognosis and Visual Outcomes

Visual outcomes are often poor regardless of management approach. 3 Final visual acuity ranges from 6/6 (normal) to no perception of light, with some eyes requiring enucleation. 3

Prognostic factors:

• Fungal etiology confers better prognosis than bacterial 3
• Coagulase-negative staphylococcal endophthalmitis has better outcomes than streptococcal 4
• Klebsiella species (more common in East Asian populations with liver abscess) have particularly poor outcomes, with 3 of 5 enucleated eyes in one series 3
• Speed of treatment initiation is critical for saving vision 4

Critical Pitfalls to Avoid

Do not:

• Delay ophthalmology consultation while attempting outpatient management 8
• Assume absence of fever rules out endophthalmitis 5
• Rely solely on systemic antibiotics without intravitreal injection 2, 4
• Miss the diagnosis by attributing symptoms to conjunctivitis—conjunctivitis does not cause severe vision loss or hypopyon 8

Do:

• Maintain high index of suspicion in any IV drug user with eye complaints 3
• Recognize that 78% of endogenous endophthalmitis cases have identifiable risk factors, with IV drug abuse being a major contributor 3
• Understand this is an ophthalmologic emergency requiring same-day intervention 5, 4