Acanthamoeba Keratitis in the Absence of Predisposing Risk Factors

Introduction: Free-living amoebae of the genus Acanthamoeba produce a progressive infection of the cornea termed Acanthamoeba keratitis. Recrudescent disease is rare but has been described as late as five years after initial treatment of the condition. Here we report a case of recrudescent Acanathamoeba keratitis, discuss useful diagnostic techniques and treatments currently available.

Case Presentation: A forty-four-year-old female contact lens wearer was treated for Acanthamoeba keratitis affecting her right eye with propamidine isothionate or Brolene 0.01% and polyhexamethylbiguanide or PHMB 0.02% for six months. Fifteen months later she re-presented with recurrence of right eye pain and redness. Limbal injection, peripheral stromal haze and radial keratoneuritis were apparent. Resolution of these symptoms and signs occurred after re-treatment with PHMB 0.02%. The patient maintained a visual acuity of 6/7.5.

Discussion: One other case of delayed recurrence of Acanthamoeba keratitis in a patient with no obvious risk factors has been described. Despite apparent clinical resolution of an initial infection, viable Acanthamoeba cysts may persist, dormant, in the cornea. Their reactivation causes recurrence and may be due to an alteration in ocular defence mechanisms. Options for the treatment of Acanthamoeba keratitis have expanded.

Keywords: Acanthamoeba; Keratitis; Contact lenses; Treatment.