Diagnostics and management approaches for Acanthamoeba keratitis

ABSTRACT

Introduction

With less than 3 new cases per million people, Acanthamoeba keratitis (AK) is an orphan disease. It is a potentially devastating ocular infection without standardized guidelines for diagnostics and treatment.

Areas covered

A comprehensive Pubmed and Clinical Trial search has been performed to summarize current diagnostics and management approaches for AK before March 2020. Ophthalmologists must recognize its clinical signs, such as gray-dirty epithelium, pseudodendritiformic epitheliopathy, perineuritis, multifocal stromal infiltrates, and ring infiltrate for a timely adequate treatment. In later stages, scleritis, iris atrophy, anterior synechiae, secondary glaucoma, mature cataract, and chrorioretinitis are referred to as classical clinical signs. A clinical suspicion must be followed by laboratory diagnostics using confocal microscopy, polymerase-chain-reaction (PCR), microbiological culture, and/or histopathological examination. The first randomized clinical drug trial for the treatment of AK is planned to be completed in 2021.

Expert opinion

Up to date, as conservative treatment up to 1 year, triple-topical therapy (polyhexamethilen-biguanide, propamidine-isethionate, neomycin) and, in therapy-resistant cases, surgical treatment in form of corneal cryotherapy, riboflavin-UVA crosslinking and penetrating keratoplasty is used. In our opinion, a specific medical treatment should be clinically applied in the future, following isolation of the pathognomic Acanthamoeba strain, and after in vitro culturing and testing.

KEYWORDS:

• Acanthamoeba keratitis
• orphan disease
• orphan drug
• triple-therapy

Article highlights

• Ophthalmologists should be able to recognize early clinical signs of AK such as gray-dirty epithelium, pseudodendritiformic epitheliopathy, perineuritis, multifocal stromal infiltrates, and ring infiltrate.

• In later stages, scleritis, iris atrophy, anterior synechiae, secondary glaucoma, mature cataract, and chrorioretinitis are referred to as clinical signs of progressive severity of AK.

• It is essential that a clinical suspicion is followed by immediate adequate diagnostics using confocal microscopy, polymerase-chain-reaction (PCR), microbiological culture, and/or histopathological examinations.

• The first randomized clinical drug trial for the treatment of AK is planned to be completed in 2021.

• Until now, a topical triple-therapy (polyhexamethilen-biguanide, propamidine-isethionate, neomycin) is applied as conservative treatment up to 1 year after the onset of AK.

• Surgical treatment options include corneal cryotherapy, riboflavin-UVA crosslinking and penetrating keratoplasty which is often followed by amniotic membrane transplantation due to persistent epithelial defects on the graft.

This box summarizes the key points contained in the article.

Acknowledgments

The authors would like to acknowledge the work of Dr. Szentmáry at the Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Aniridia Research, supported by the Dr. Rolf M. Schwiete Foundation.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership, or options, expert testimony, grants, or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.