Atypical Acanthamoeba Keratitis In A 13-Year-Old: The Importance Of Suspecting The Unsuspected.

To report an atypical presentation of Acanthamoeba keratitis in a non–contact lens–wearing pediatric patient and to emphasize the importance of maintaining a high index of clinical suspicion in cases of presumed herpetic keratitis unresponsive to standard antiviral therapy. Additionally, this report aims to highlight the decisive role of in vivo confocal microscopy and multimodal imaging in achieving early diagnosis and improving visual outcomes.

This case was managed in a specialized ophthalmology referral center. Diagnostic evaluation included slit-lamp biomicroscopy, in vivo confocal microscopy (IVCM), pachymetry, and anterior segment optical coherence tomography (AS-OCT). The patient was treated and followed for 12 months in an outpatient clinical setting, adhering to institutional ethical standards.

A 13-year-old female, non-contact lens wearer, presented with a 1-month history of progressive redness, photophobia, and blurred vision in the left eye (OS). She had failed empirical topical ganciclovir. Examination of OS revealed mild hyperemia and a well-demarcated, deep circular stromal lesion without a ring infiltrate. Fluorescein showed punctate keratitis but no frank defect. In vivo confocal microscopy (IVCM) was definitive, showing hyperreflective epithelial patterns and double-walled structures (cysts/trophozoites). Pachymetry confirmed focal superior thinning (447 µm), and AS-OCT showed anterior stromal hyperreflectivity consistent with leukoma. Treatment with 0.02% chlorhexidine, fluorometholone, and oral acyclovir led to a favorable 12-month follow-up with no recurrence. 

AK is an uncommon but vision-threatening infection often misdiagnosed due to non-specific findings. A high index of suspicion is essential, even in patients without classic risk factors such as contact lens wear. Early recognition of suggestive signs, supported by timely use of diagnostic tools like IVCM and molecular testing, allows prompt initiation of targeted therapy. This approach improves visual outcomes and reduces complications. Multimodal imaging plays a key role in the management of atypical infectious keratitis, enabling early detection before irreversible corneal damage occurs.