Going Dutch on Acanthamoeba Keratitis

An effective treatment for Acanthamoeba keratitis could soon be available, a Dutch study suggests.

This topic is particularly crucial, said Yexin Ye MD, as although the organism is rare, it is vision-threatening and there is currently no international consensus on its treatment.

Dr Ye reported that, according to the Dutch Ophthalmic Society, the best course of action for Acanthamoeba keratitis is to start treatment immediately. She said the society recommends either combination therapy using biguanide and diamidine or monotherapy with biguanide alone.

However, despite prescribed aggressive treatment, patient outcomes remain poor.

“Without adequate treatment, 80.4% of patients affected by Acanthamoeba keratitis require keratoplasty or enucleation without anti-amoebic therapy,” Dr Ye said.

Enter polihexanide 0.8 mg/mL. Currently the only EMA-approved treatment for Acanthamoeba keratitis, it is a polymeric biguanide active against Acanthamoeba trophozoites and cysts.

Dr Ye said her study presents the first real-world experience of using polihexanide 0.8 mg/mL to treat Acanthamoeba keratitis in the Netherlands. Conducted as a retrospective case study involving eight patients between October 2022 and March 2025, under which the drug was administered according to compassionate use, pre-market guidelines.

All but one of the patients were contact lens wearers whose diagnoses were primarily confirmed by polymerase chain reaction/corneal culture. All had been treated with antibiotics, 62.5% with corticosteroids and 50% with antivirals. The majority, 75%, were in stage II of the disease.

Days from symptom onset ranged from 21 to 1,201. Duration of treatment ranged from 203 days to more than 100, respectively. Most patients had prolonged symptoms and experienced prior treatment.

While one patient had to discontinue topical application of polihexanide 0.8 mg/mL due to a toxic response, Acanthamoeba keratitis was otherwise resolved in six out of eight patients with no signs of active infection or inflammation after epithelial closure and no required enucleations. The treatment of the remaining patients is ongoing.

Images of one of the patients’ eyes showed clear, visible improvement after treatment with polihexanide. In this case, no vision improvement surgery was necessary, though 50% of patients involved in the study did require it.

Concluding, Dr Ye said the fact no enucleations or keratoplasties were required for the patients in the study, who may otherwise have had an 80% chance of undergoing these procedures, “highlights the efficacy of polihexanide 0.8 mg/mL.” She expressed hope for more trials into the use of this treatment, especially to help reduce potential toxic response.

Dr Ye presented at the 2025 EuCornea conference in Prague.

Yexin Ye MD, BSc is a PhD candidate in ophthalmology at the University of Maastricht, Netherlands. yexin.ye@mumc.nl