Host Response and Pathogen Load in Acanthamoeba Keratitis: A Histopathological Analysis.

Area of Science:

• Ophthalmology
• Infectious Diseases
• Pathology

Background:

• Acanthamoeba keratitis (AK) is a severe microbial infection of the cornea.
• Histopathological features are crucial for understanding AK pathogenesis and clinical outcomes.
• Surgical management, such as therapeutic penetrating keratoplasty (TPK), is often required for advanced AK.

Purpose of the Study:

• To investigate the histopathological characteristics of Acanthamoeba keratitis (AK).
• To correlate organism morphology, density, and distribution with the host's inflammatory response.
• To associate these histopathological findings with clinical parameters in surgically treated AK cases.

Main Methods:

• Retrospective case series of histopathologically confirmed AK cases undergoing TPK.
• Analysis of demographic, clinical, microbiological, and histopathological data.
• Histologic evaluation included organism type (cyst/trophozoite), density, stromal location, inflammation, and margin status; statistical tests were used for associations.

Main Results:

• Twenty-three eyes were analyzed; cystic forms predominated (56.5%) with diffuse stromal involvement (56.5%).
• Acute inflammation was more frequent with higher organism loads (87.5% vs. 46.7%).
• Younger patients showed diffuse infection (34.2 years vs. 47.8 years); margin positivity did not correlate with severity or recurrence.

Conclusions:

• Acanthamoeba keratitis exhibits significant variability in organism distribution and inflammatory response.
• Tissue damage in AK is likely immune-mediated rather than solely organism load-dependent.
• Persistent cysts contribute to recurrence, highlighting the need for early diagnosis and prolonged anti-amoebic therapy.