Case series: IV pentamidine and keratoplasty with adjunctive cryotherapy in the treatment of polytherapy- resistant Acanthamoeba keratitis

Purpose To report two cases of Acanthamoeba Keratitis (AK) treated with intravenous pentamidine and penetrating keratoplasty with adjunctive cryotherapy, post-polytherapy. Design Retrospective, noncomparative case series Patients and methods Medical records and histopathological features in corneal surgical specimens from two patients who presented with AK that were successfully treated with intravenous (IV) pentamidine and keratoplasty with adjunctive cryotherapy were reviewed. Results A 24-year-old female and a 60-year-old female, both with a history of soft contact lens use, were diagnosed with AK after each presenting with unilateral corneal ulcers and ocular discomfort. These patients underwent treatment courses of various antimicrobial and antiamoebic pharmaceuticals including ofloxacin 0.3%, neomycin-polymyxin- gramicidin 1.75 mg-10000 unit-0·025 mg/mL, chlorhexidine 0.02%, polyhexamethylene biguanide (both 0.02% and 0.08%), propamidine isethionate 0.1%, hexamidine 0.1%, voriconazole 1%, and more. However, the treatment that appeared to ultimately eradicate the protozoan infection involved a two-week course of IV pentamidine (4 mg/kg) every 24 hours, followed by keratoplasty with adjunctive cryotherapy. Conclusion In polytherapy-resistant cases of AK, treatment can be attempted using IV pentamidine followed by keratoplasty with cryotherapy. Earlier consideration of AK in the differential diagnosis can allow for timely intervention; nevertheless, AK can demonstrate therapeutic resistance and still progress to advanced vision- and eye-threatening stages if there is therapeutic resistance. In these instances, knowledge of successful treatment using less common modalities and agents, such as described in this paper, can be valuable to clinicians battling to eradicate a challenging infection such as AK.