Contact Lens-Related Microbial Keratitis With Hypopyon
A 23-year-old college student who wears monthly soft contact lenses, including during overnight sleep and swimming, presents with a 3-day history of left-eye pain, photophobia, and decreasing vision. He has been using an over-the-counter lubricant without improvement. He reports sleeping in his lenses 2–3 nights per week and rinsing the case with tap water. Visual acuity is 20/100 OS and 20/20 OD. Slit-lamp examination shows a 4-mm central corneal stromal infiltrate with an overlying epithelial defect, 2+ anterior chamber cells, and a 1-mm hypopyon. The conjunctiva is intensely injected. He is otherwise healthy, afebrile, and has no history of ocular surgery or herpes. He asks whether he can simply switch to daily disposable lenses and use antibiotic drops.
1. State your diagnosis and immediate management, including whether you would perform corneal cultures and why.
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Diagnosis: contact-lens-related microbial keratitis. The central stromal infiltrate, overlying epithelial defect, hypopyon, and acute course suggest bacterial infection, most likely Pseudomonas aeruginosa. Fungal and Acanthamoeba keratitis remain in the differential, especially given tap-water rinsing and poor lens hygiene.
Immediate management:
- Discontinue contact lens wear immediately; discard the current lens and case, or send them for culture if a laboratory is available.
- Perform corneal scrapings for Gram stain, bacterial culture, fungal culture, and special stains or confocal microscopy if Acanthamoeba is suspected. Culture is indicated for sight-threatening, central, large (greater than 2 mm), or hypopyon-associated infiltrates because it identifies the organism and guides therapy if the patient fails to improve.
- Start empiric fortified topical antibiotics: cefazolin 50 mg/mL and tobramycin 14 mg/mL alternating every 30–60 minutes around the clock, or moxifloxacin 0.5% every hour if fortified agents cannot be compounded. Coverage must include Pseudomonas.
- Do not patch the eye. Do not start a topical corticosteroid until the infection is controlled, typically after 24–48 hours of appropriate antibiotics with clear clinical improvement; steroids can worsen fungal or Acanthamoeba infection.
- Arrange follow-up within 24 hours and then daily until the infiltrate is resolving. Urgent cornea referral or admission is warranted for a large central infiltrate, hypopyon, or impending perforation.
2. The infiltrate enlarges after 48 hours of hourly fortified antibiotics. How do you reason through the differential and adjust management?
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First, verify adherence and technique. Ask who is administering drops, how often, and whether the patient is waking at night. Poor compliance is a common reason for apparent treatment failure.
Reconsider the organism. An enlarging infiltrate despite appropriate antibacterial coverage raises resistant bacteria, fungus, or Acanthamoeba. Fungal keratitis may show feathery margins, satellite lesions, or a dry, elevated infiltrate; Acanthamoeba may present with severe pain out of proportion to signs, radial keratoneuritis, or a ring infiltrate. Review the original scrapings and repeat cultures, including corneal biopsy if needed. Confocal microscopy can help identify Acanthamoeba cysts.
Adjust therapy:
- If bacterial resistance is suspected, add or switch to fortified vancomycin 25–50 mg/mL for gram-positive coverage and consider an aminoglycoside or fourth-generation fluoroquinolone for gram-negative coverage.
- If fungal infection is suspected, start topical natamycin 5% for filamentous fungi or topical voriconazole 1% for yeast or deep stromal involvement; consider systemic therapy for deep infection.
- If Acanthamoeba is suspected, start a biguanide (polyhexamethylene biguanide 0.02% or chlorhexidine 0.02%) plus a diamidine (propamidine 0.1%), with frequent dosing.
- Do not add steroids while the infection is worsening.
Escalate care: refer urgently to a cornea specialist for possible admission, intensive topical therapy, or surgical intervention if there is progressive thinning or perforation risk.
3. What follow-up, counseling, and referral criteria would you set for this patient after the infection resolves?
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Follow-up: continue frequent topical antibiotics until the epithelial defect heals and the infiltrate scars. Then taper slowly according to clinical response. Monitor for corneal thinning, perforation, and secondary glaucoma; check IOP and perform a dilated fundus examination if the view is adequate. A residual corneal scar may cause irregular astigmatism; assess refraction and consider rigid gas-permeable fitting or specialty contact lenses after stability.
Counseling: explain that overnight wear and exposing lenses to water are the major modifiable risk factors. Recommend daily disposable lenses if contact lens wear resumes, never sleeping or swimming in lenses, replacing lenses and cases on schedule, and using fresh multipurpose solution or hydrogen peroxide systems. He should discard the current case and any opened solution. Advise seeking care urgently for pain, redness, or vision change rather than using OTC drops.
Referral criteria: refer to cornea if the infiltrate is central and large, if there is progressive thinning or perforation, if the infection fails to improve within 48–72 hours, or if a fungal or Acanthamoeba etiology is confirmed. Also refer if the patient cannot comply with frequent drop schedules or follow-up. Document that contact lens wear should not resume until the cornea is fully healed and the patient has been re-educated about hygiene.