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The diagnostic value of a ring infiltrate in acanthamoebic keratitis
Abstract:
During the past ten years it has become increasingly apparent that acanthamoebae can directly infect the cornea, usually after trauma, associated with contaminated water or soft contact lens wear. Thirteen cases of acanthamoebic keratitis have been published. In only three of these cases was the diagnosis first made by microbiologic methods, while in the others it was made only after pathologic examination of resected corneal specimens or enucleated eyes. We report three additional cases, two of which were accurately diagnosed by corneal scrape-smears and cultures before penetrating keratoplasty was performed. The reason for the accurate laboratory diagnosis in these cases was the presence of a diagnostic paracentral annular corneal infiltrate or abscess, a feature identified in over two-thirds of the earlier cases but one which has not been adequately emphasized or pursued for its early diagnostic value. We review the other clinical and epidemiological features of this entity, microbiological diagnostic techniques, the pathologic aspects, the role of topically and systemically administered medicaments, and finally point out the almost unavoidable role of penetrating keratoplasty after the temporizing effects of medical treatments have been achieved.
Insights
Acanthamoeba keratitis, an infection of the cornea, is often diagnosed late. Early diagnosis is possible through recognizing specific corneal infiltrates, improving treatment outcomes.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Acanthamoeba keratitis is an infection of the cornea, often linked to trauma, contaminated water, or contact lens use.
- Previous diagnoses were frequently delayed, relying on pathological examination rather than early microbiological methods.
Observation:
- This study presents three new cases of Acanthamoeba keratitis.
- Two cases were accurately diagnosed pre-operatively using corneal scrape-smears and cultures.
- A key diagnostic feature, a paracentral annular corneal infiltrate or abscess, was noted in most cases.
Findings:
- The paracentral annular corneal infiltrate/abscess, present in over two-thirds of previously reported cases, is a crucial, yet underemphasized, early diagnostic sign.
- Microbiological techniques, including scrape-smears and cultures, are vital for timely diagnosis.
Implications:
- Early recognition of the characteristic corneal infiltrate can lead to prompt microbiological diagnosis and treatment.
- While medical treatments are important, penetrating keratoplasty remains a common surgical intervention for Acanthamoeba keratitis.