Different Forms Of Presentation Of Infectious Amebic Keratitis.

The aim of this study is to describe three clinical cases of Acanthamoeba keratitis with variable and nonspecific presentations to highlight the challenges in its differential diagnosis and the importance of confocal microscopy as a technique of high sensitivity and specificity

Case series from patients managed at Hospital Universitario Central de Asturias, a tertiary referral academic hospital in Oviedo, Spain.

Description of 3 clinical cases of recent diagnosis of acanthamoeba keratitis in our center with different forms of presentation.

In Case 1, after a poor response to antivirals and a negative PCR test, confocal microscopy detected amebic cysts; the condition finally resolved with 1% propamidine. Case 2 presented with severe pain and perineural infiltrates; the diagnosis was confirmed by microscopy, and the patient responded well to hexamidine and chlorhexidine. Case 3 showed annular edema and a lack of response to initial treatment; after confirmation by microscopy, a lamellar keratoplasty was successfully performed. In all cases, confocal microscopy was crucial for diagnosis in the face of negative cultures and an initial erroneous clinical suspicion.

Acanthamoeba keratitis presents a significant diagnostic challenge because its clinical presentation can resemble that of herpes simplex, bacteria, and fungi. The diagnosis should not be ruled out in cases of keratitis that only partially stabilizes with antiviral, antibiotic, or corticosteroid treatment. Techniques such as PCR, histology, and cultures can be performed, but due to their low sensitivity, they can produce a high rate of false negatives. Therefore, confocal microscopy should be considered, as it offers high sensitivity and specificity.