Optimizing early diagnosis and treatment of acanthamoeba keratitis through corneal scraping

Acanthamoeba keratitis (AK) is a sight-threatening disease, commonly associated with contact lens use. Early diagnosis is challenging due to its varied clinical presentation. This study aimed to describe the clinical characteristics of AK and evaluate the utility of corneal scraping for early diagnosis.

This retrospective study included 14 eyes from 13 AK patients diagnosed by detecting Acanthamoeba cysts in corneal scrapings between July 2019 and August 2023. Clinical history, presentation, treatment, and outcomes were analyzed.

The mean age of the 13 patients was 28 ± 13 years. Ten patients used soft contact lenses and 3 patients used orthokeratology lenses. The mean time from symptom onset to diagnosis was 18.2 ± 12.9 days. The most common sign was elevated superficial punctate keratitis (SPK), followed by dot infiltrates, radial perineuritis, pseudodendrites, stromal edema, and ring infiltrates. Nine eyes were treated with polyhexamethylene biguanide (PHMB) eye drops, while the remaining five eyes received a combination of two or three anti-amoebic agents. Thirteen eyes improved with treatment, but one eye-initially misdiagnosed and treated with steroids-required therapeutic keratoplasty. LogMAR visual acuity in eleven eyes improved from an initial 0.51 ± 0.44 to 0.11 ± 0.10 after treatment.

Elevated SPK is the most frequent early feature of AK and may mimic contact lens-related sterile keratitis. Corneal scraping is a valuable diagnostic tool that enables earlier detection and improved outcomes. PHMB monotherapy is effective in early AK, while delayed diagnosis and prior steroid use may lead to disease progression and necessitate surgical intervention.