Acanthamoeba keratitis is a rare but serious complication of
contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe
pain, sometimes disproportionate to the signs, with an early superficial
keratitis that is often misdiagnosed as herpes simplex virus (HSV)
keratitis. Advanced stages of the
infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of
contact lens-related
Acanthamoeba keratitis that occurred in Australia and New Zealand over a three-year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for
Acanthamoeba keratitis were
contact lens wear with inappropriate or ineffective lens maintenance and exposure of the
contact lenses to tap or other sources of water. All six patients responded well to medical
therapy that involved topical use of appropriate therapeutic agents, most commonly
polyhexamethylene biguanide and
propamidine isethionate, although two of the patients also subsequently underwent deep
lamellar keratoplasty due to residual corneal surface irregularity and stromal
scarring. Despite the significant advances that have been made in the medical
therapy of
Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear
contact lenses must be thoroughly educated about the proper use and care of the
lenses. In particular, exposure of the
contact lenses to tap water or other sources of water should be avoided.