ODAK Phase 3 (043/SI)

Acanthamoeba keratitis (AK) is an uncommon, severe, corneal infection, first described in 1975. Over 90% of cases are in contact lens users, and result from exposure to contaminated fluids. The international incidence is highest in the UK (50 to 200 new cases per year in England) probably due to contamination of domestic tank-stored water. Acanthamoeba is a single celled organism and difficult to eradicate in the cyst form, in which it survives in the cornea. The infection is persistent, accompanied by debilitating pain and inflammation, with current best treatment curing only 70% of patients in 12 months. In 1992 unlicensed PHMB 0.02% eye drops were introduced, becoming a treatment breakthrough. Before this only 1 of the first 20 patients treated had a good outcome. PHMB 0.02%, to which there is no resistance in laboratory tests, was rapidly introduced world-wide and often combined with propamidine (Brolene), a less effective drug introduced earlier. Although 70% of cases are cured with this combination a major reason for the 30% with a poor outcome is due to poor penetration of the drug. Because the development work, to assess the safety of PHMB as an eye drop had not been done, higher concentrations of PHMB, with better penetration, have not been assessed. The Orphan Drug for AK (ODAK) project was EU funded in 2012 to carry out the studies needed to develop PHMB as a licensed drug for AK. These have resulted in the development of concentrated PHMB 0.08%, which is expected to reduce treatment failures. This proposed randomised controlled trial, comparing PHMB 0.08% to PHMB 0.02% and Brolene, is the last study required by the European Medicines Agency to license PHMB 0.08% as treatment for AK. A successful outcome will be a major step forward for patients, resulting in an effective licensed preparation.