Painless acanthamoeba keratitis

Background: Acanthamoeba keratitis is a severe, painful corneal infection f ound in contact lens wearers. The entity can easily be confused with herpet ic or fungal keratitis, especially if no ocular pain is reported. History and signs: A 32-year old myopic female presented a unilateral kerat itis of unknown etiology since 3 weeks. Administration of topical antiviral substances and corticosteroids led only to temporary improvement of the co ndition. The patient complained of photophobia but not of ocular pain. The affected eye showed corneal edema, central stromal thickening, descemet's s triae as well as fibrin deposits on the corneal endothelium and in the ante rior chamber. Diagnosis: An aqueous specimen was negative for a viral infection. A cultur e for bacteria was negative. Staphylococci were cultured from corneal scrap ings and Enterococci from the contact lens solution. Another corneal scrapi ng revealed Acanthamoeba class II (6 weeks after the onset of symptoms). Clinical course: Under treatment with propamidine, polymyxin b, neomycin, g ramicidin and polyhexidine (topical) as well as fluconazole/ketoconazole (s ystemic) the diameter of the annular infiltrate, which had developed decrea sed, but the infiltrate persisted. In the further course, the infiltrate pe rsisted while the amount of fibrin in the anterior chamber increased. Penet rating keratoplasty was performed. Histologic examination of the host corne al tissue revealed massive infiltration with Acanthamoeba. Conclusion: Severe pain and history of wearing contact lenses are features suggestive of Acanthamoeba keratitis. The patient presented here had a hist ory of contact lens wear, but no ocular pain was reported. The characterist ic annular infiltrate had a late onset. Bacterial superinfection could not be ruled out. Therapeutic penetrating keratoplasty had to be performed as t he condition deteriorated inspite of intensive chemotherapy. With penetrati ng keratoplasty a good visual acuity could be regained.