Results of a 10-year retrospective study in Italy and the United Kingdom conducted by ODAK
A 10-year retrospective study was conducted utilising records from patients affected by AK treated from 1997 to 2007 at two eye hospitals in Europe, Moorfields Eye Hospital NHS Foundation Trust London (UK) and San Raffaele Scientific Institute Milan (Italy).
The primary end point of the study was the clinical resolution rate (CRR) defined as percentage of patients cured one month after discontinuing all therapies. Secondary end points of the study were visual acuity, rate of patients requiring keratoplasty, duration of treatment and incidence of adverse events (AEs).
100 patients were evaluated of which ninety six were contact lens wearers. In 84 cases diagnosis was based on either culture or histology. The mean time delay between the onset of symptoms and diagnosis was 51 days. The most common signs and symptoms observed were pain (50%) and Infiltrates (24%). Many patients (40%) had very low vision at diagnosis.
83% of patients were treated with multiple agents. PHMB was the most used drug. PHMB and a diamidine (hexamine or propamidine) was used as a combination therapy in 51% of cases.
The CRR was 86%. Keratolasty was performed in 24 patients. 14 patients not cured medically had therapeutic or tectonic keratoplasty. In 10 patients keratoplasty was executed to restore vision.
When patients were allocated to the treatment which was considered related to the outcome of AK, patients treated with monotherapy (PHMB or Chlorohexidine) had a higher CRR (96-100%) than those treated with combination therapy (80-90%). All differences were not statsistically significant.
A total of 31 AEs occurred during the study. 21 had a relationship to treatment, 19 AEs were considered serious. The most common AE was ocular toxicity which occurred in 9 patients. Of these, 6 cases were related to the use of diamidines, with the 3 remaining to biguanides (2 to PHMB).
PHMB was the most used medication for patients with AK in this study. This data suggests PHMB used as a monotherapy has a good risk to benefit ratio and is a good candidate for a new drug licensing application.
In vivo evaluation of polyhexamethylene biguanide eye drops efficacy in a rat Acanthamoeba polyphaga keratitis conducted by ODAK