Acanthamoeba Keratitis: New Hope for an Underdiagnosed Infection

Acanthamoeba keratitis is a rare but severe corneal infection mainly affecting contact lens users. With around 15 million contact lens wearers in Mexico, even a small infection rate could impact thousands. Although rare, global incidence is increasing. Yet, a newly approved treatment offers renewed hope for patients.

Acanthamoeba keratitis is a parasite-driven infection that causes significant pain and vision loss, sometimes leading to blindness. It primarily affects contact lens users, accounting for more than 90% of reported cases, particularly when lenses are worn in high-risk environments or with inadequate hygiene, reports The National Center for Biotechnology Information (NCBI). 

Globally, the incidence ranges from 0.13 to 33 cases per million among contact lens wearers. In the general population, it occurs in one to nine per 100,000 people, highlights Ciencia Latina Revista Científica Multidisciplinar.  The condition is often underdiagnosed due to its rarity and non-specific early symptoms. In Mexico, limited diagnostic infrastructure may further obscure actual prevalence.

While Acanthamoeba keratitis represents one of the most severe complications associated with contact lens use, patients are also at risk of a range of more common ocular conditions. These include dry eye syndrome, allergic and infectious conjunctivitis, corneal ulcers, microbial or amoebic keratitis, hypoxia-induced complications, and mechanical damage resulting from poor lens fit or prolonged wear.

According to the NCBI, more than 75% of Acanthamoeba keratitis cases are initially misdiagnosed. Although corneal scraping remains the diagnostic gold standard, emerging techniques, such as polymerase chain reaction (PCR), impression cytology, and confocal microscopy, have significantly improved early detection, especially in patients pre-treated with antibiotics.

Clinically, Acanthamoeba keratitis is characterized by severe photophobia, foreign body sensation, progressive visual loss, perineural infiltrates, and the presence of a distinctive ring-shaped stromal infiltrate, observed in approximately 50% of cases. Bilateral infections are uncommon, reported in only 4–11% of patients. Due to symptom overlap with other, more prevalent ocular infections, misdiagnosis and treatment delays are common.

In a notable advancement for both patients and ophthalmology professionals, the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) has granted marketing authorization and Promising Innovative Medicine (PIM) designation to AKANTIOR (polihexanide 0.08%), developed by SIFI. 

“The granting of the marketing authorization and PIM designation marks a significant milestone in our mission to provide access to treatment for patients with Acanthamoeba keratitis in the UK,” said Manuela Marrano, Executive Director of Regulatory Affairs and Market Access, SIFI.

Finalized in May 2025, the MHRA decision recognizes AKANTIOR as a new active substance while preserving its orphan drug designation. This builds on the product’s earlier approval in the European Economic Area in August 2024. AKANTIOR is formulated as a 0.08% polihexanide monotherapy eye drop that targets both trophozoite and cyst forms of Acanthamoeba and is delivered via a single-dose system.