Akantior (polihexanide 0.08%) is the first medicine ever licensed for acanthamoeba keratitis, approved by the UK's MHRA in May 2025. It is a single-agent antiamoebic eye drop, started intensively and tapered over several months under corneal-specialist supervision. Because delayed diagnosis is the biggest driver of poor outcomes, any contact lens wearer with a painful, light-sensitive red eye should be examined urgently — a private consultant corneal assessment typically costs £200–£350, with the Akantior course itself quoted individually as a specialist hospital-initiated medicine.
What is acanthamoeba keratitis?
Acanthamoeba keratitis (AK) is an infection of the cornea — the clear window at the front of the eye — caused by Acanthamoeba, a free-living micro-organism found in tap water, swimming pools, hot tubs, lakes and soil. It is rare, but it is one of the most serious corneal infections because the organism can form hardy cysts that resist many treatments and burrow into the corneal tissue.
The overwhelming majority of UK cases occur in contact lens wearers, particularly where lenses meet water: showering or swimming in lenses, rinsing lenses or cases with tap water, or handling lenses with wet hands.
Symptoms typically include:
- Severe eye pain — often out of proportion to how the eye looks
- Intense light sensitivity (photophobia)
- Redness, watering and blurred vision that worsens over days or weeks
- A feeling of something in the eye that doesn't settle when lenses are removed
Because early AK can resemble more common infections, it is frequently mistaken for viral or bacterial keratitis at first. If you wear contact lenses and have a painful red eye that is not improving, ask specifically about acanthamoeba — and be seen by a specialist quickly. Our guide on when to see a private ophthalmologist explains how to short-cut the wait.
Contact lens wearer with a painful, light-sensitive eye? Don't wait it out — early diagnosis is the single biggest factor in a good outcome.
Request an urgent assessmentWhat is Akantior and how does it work?
Akantior is the brand name for polihexanide 0.08% (PHMB) eye drops, developed by SIFI. Polihexanide is a polymeric biguanide that attacks both the active (trophozoite) and dormant cyst forms of Acanthamoeba — the cyst form being the reason AK has historically been so hard to eradicate.
Its significance is regulatory as well as clinical. Before Akantior, UK patients were treated with unlicensed, pharmacy-compounded combinations — typically low-strength PHMB 0.02% with propamidine — assembled case by case. In May 2025 the MHRA granted Akantior marketing authorisation as the first approved treatment for acanthamoeba keratitis in the UK, with orphan-medicine and Promising Innovative Medicine designations. It is used as monotherapy: one licensed medicine at a therapeutic concentration, with a defined dosing schedule, rather than an improvised cocktail.
What the treatment course involves
Akantior is a specialist-initiated medicine — treatment is started and supervised by an ophthalmologist experienced in corneal infection. While your consultant will tailor the schedule to your eye, a typical course follows this shape:
- Confirming the diagnosis. Slit-lamp examination, corneal imaging and, where needed, corneal sampling to confirm Acanthamoeba and rule out mixed infection.
- Intensive initial phase. Drops are instilled frequently through the waking day to drive down the organism load.
- Gradual taper. As the cornea responds, dosing frequency is stepped down in stages — never stopped abruptly — to prevent recurrence from surviving cysts.
- Completion and review. Treatment continues until the infection has fully resolved; the whole course commonly runs over several months.
Adherence matters enormously with AK: missed drops give cysts the chance to re-activate. Your care team will give you a written schedule and adjust it at each review.
Monitoring and recovery
First days
Frequent specialist review while the intensive phase begins. Pain control and light-sensitivity management alongside the drops. Contact lens wear stops completely.
First weeks
Reviews track the corneal response at the slit lamp. Pain and photophobia usually ease as the organism load falls. Dosing is tapered only when the cornea shows sustained improvement.
Following months
Continued taper with progressively longer review intervals. Vision often recovers gradually as inflammation settles and the corneal surface heals.
After the course
Final reviews confirm the infection is eradicated. Where scarring has affected vision, options range from specialist scleral contact lenses to corneal transplantation for the most severe cases.
Most patients treated promptly do not need surgery. Where dense central scarring remains after cure, your consultant may discuss a corneal transplant — see our guides to DALK (deep anterior lamellar keratoplasty) and penetrating keratoplasty costs.
What does private treatment cost?
Because acanthamoeba keratitis is rare and every course is individually supervised, pricing has two parts:
- Consultant corneal assessment: typically £200–£350, including slit-lamp examination and imaging where indicated. Follow-up reviews are usually charged from around £150.
- The Akantior course: quoted individually. Akantior is a hospital-initiated orphan medicine, and the quantity needed depends on the length of your taper — your consultant will give you a written estimate before treatment starts.
If you have private medical insurance, corneal infection treatment is usually covered as acute care — check pre-authorisation with your insurer. Browse all eye conditions we treat or our full treatments A–Z.