The European Medicines Agency (EMA) has recently approved the use of Akantior (polyhexanide, 0.08% or 0.8 mg/ml) for the treatment of acanthamoeba keratitis. Acanthamoeba keratitis is an infection of the cornea, the transparent outer layer at the front of the eye. The infection is usually the result of improper use of contact lenses. This can occur if they are not removed before bathing, showering or sleeping or are kept in water instead of a special lens solution.
Acanthamoeba is a type of parasite found very commonly in nature, especially in soil and in most types of water (except the sea, due to the presence of salt). Acanthamoeba keratitis is rare, but very serious when it does occur. It causes a lot of pain for the patient.
The multicentre study, which the Clínic's Institute of Ophthalmology participated in, estimated an incidence of 1 case per 30,000 inhabitants a year in Spain of infectious keratitis due to contact lenses. Of these, only a small part were secondary to Acanthamoeba.
"It is thought that the incidence has increased recently, since the study included the years of the pandemic, when more use of glasses and less of contact lenses would have been expected," explained Dr Josep Torras, an ophthalmologist at the Clínic.
Advances in diagnosis and treatment
Until recently, the only marketed treatments for this pathology were available solely in the United Kingdom, under the trade names Brolene and GoldenEye. It had to be purchased as foreign medication in Spain. Many cases of this pathology, however, have been successfully treated at the Clínic with 0.02% chlorhexidine eye drops (a very well-tolerated antiseptic), but this requires compounding by the Hospital's pharmacists.
The commercial accessibility of Akantior (polyhexanide) is a great advance, as it allows for effective treatment to be available in all European pharmacies.
It is very important to diagnose this disease early so that treatment is more effective. Once the parasite is embedded in the cornea, medication is less effective. If the patient does not respond well to the treatment, that is, resistance develops, or treatment is started too late, a corneal transplant may be required, which does not always evolve satisfactorily. Vision in the eye may be lost in these cases.
To improve the diagnosis of affected people and ensure it is made early, the use of the PCR test is essential to detect this parasite. This test has proven to be more sensitive than the cultures that were previously needed for diagnosis.
Prevention, the best treatment
Although effective treatment for this infection has now been achieved, there are still other eye infections, also related to the use of contact lenses, for which there is no commercial treatment available. This is the case with fungal infections (filamentous or yeast), which also require the compounding of eye drops by hospital pharmacists; however, this slows down treatment and increases costs.
Finally, contact lens users should be made aware that the best treatment is prevention; that is, improving contact lens hygiene, by removing them before sleeping or bathing. Not doing so increases the risk of a corneal infection, which can have very serious consequences for their sight.
INFORMATION DOCUMENTED BY:
Dr Josep Torras, Clinical Institute of Ophthalmology, Hospital Clínic Barcelona.
