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Acanthamoeba Keratitis

Severe parasitic corneal infection associated with contact lens use, characterized by disproportionate pain, ring infiltrate, and risk of visual loss without prompt antiamoebic therapy.

Written by: Saygı Hospital Health Guide Editorial Board
Published:

This content is for general information; please consult your physician for diagnosis and treatment.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Göz Hastalıkları department. Book Appointment →

What is Acanthamoeba Keratitis?

Acanthamoeba spp. are ubiquitous free-living protozoa found in soil, water, and air. Trophozoites adhere to corneal epithelium via mannose receptors after a microtrauma or contact lens wear; cyst forms (double-walled, resistant) make eradication difficult. Risk factors include exposure to tap-water rinsing of lenses, swimming or showering with lenses, and inadequate disinfection.

Clinical course evolves over weeks: epithelial irregularities and pseudodendrites in early stage, perineural infiltrates along corneal nerves (radial keratoneuritis — pathognomonic), ring infiltrate in stromal phase, and risk of corneal melting, scleritis, or perforation if untreated.

Diagnosis: in vivo confocal microscopy (high-yield, shows cysts), corneal scraping for stains (calcofluor white, KOH) and culture on non-nutrient agar with E. coli overlay, PCR. Differential includes herpetic keratitis, fungal keratitis, and bacterial keratitis.

Symptoms

Severe ocular pain disproportionate to clinical findings
Photophobia, tearing, foreign body sensation
Decreased visual acuity
Pseudodendritic epithelial defects in early disease
Radial keratoneuritis (perineural infiltrates)
Ring-shaped stromal infiltrate
Conjunctival injection and chemosis
Hypopyon in advanced cases

Risk Factors

Soft contact lens wear (>85% of cases)
Tap water rinsing or storage of contact lenses
Swimming, showering, or hot tub use with lenses
Use of homemade saline or expired solutions
Inadequate lens hygiene and case replacement
Corneal microtrauma, refractive surgery
Exposure to contaminated water in agricultural or rural settings

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Severe eye pain disproportionate to redness — same-day cornea specialist referral
  • Contact lens wearer with persistent keratitis unresponsive to topical antibiotics — suspect Acanthamoeba
  • Perineural corneal infiltrates on slit-lamp
  • Ring infiltrate or stromal melting
  • Sudden visual decline in chronic keratitis

Treatment Methods

01
First-line antiamoebic: biguanide (PHMB 0.02–0.08% or chlorhexidine 0.02–0.2%) every hour day and night for 48–72 hours, then taper over months
02
Combination with diamidine (propamidine isethionate 0.1% or hexamidine 0.1%) hourly to enhance efficacy against cysts and trophozoites
03
Adjunctive: cycloplegics for pain, topical NSAIDs cautiously, oral analgesics, doxycycline for collagenase inhibition
04
Avoid topical corticosteroids in early disease — may exacerbate; consider only after 2 weeks of antiamoebic therapy under specialist guidance
05
Discontinue contact lens use during entire treatment course
06
Therapeutic penetrating keratoplasty for non-healing ulcer, perforation, or visually significant scar — high recurrence rate
07
Long-term follow-up: months to years of slow taper, monitor for recurrence, address cataract or scar complications
08
Prevention: contact lens hygiene education, no tap water exposure, daily disposable lenses preferred

Which Department to Visit?

You can visit our Göz Hastalıkları department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.