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Correlation of ex vivo and in vivo confocal microscopy imaging of Acanthamoeba
  1. Noor Alantary1,2,
  2. Wayne Heaselgrave1,
  3. Scott Hau3
  1. 1 Dept Biomedical Science, University of Wolverhampton Faculty of Science and Engineering, Wolverhampton, UK
  2. 2 Aston Medical School, Aston University, Birmingham, UK
  3. 3 External Disease, Moorfields Eye Hospital, London, UK
  1. Correspondence to Dr Wayne Heaselgrave, Biomedical Science, University of Wolverhampton Faculty of Science and Engineering, Wolverhampton WV1 1LY, UK; w.heaselgrave{at}


Background/aims The aim of this study was to correlate the various forms of Acanthamoeba on ex vivo confocal microscopy (EVCM) with in vivo confocal microscopy (IVCM) and findings from cultured positive cases of Acanthamoeba keratitis.

Methods Acanthamoeba live, dead and empty cysts, and live trophozoites were prepared in vitro and inoculated into porcine cornea using a sterile 26-gauge needle and examined ex vivo using the Heidelberg Retina Tomograph II/Rostock Corneal Module. IVCM images from 12 cultured positive Acanthamoeba cases, obtained using the same instrument, were compared with EVCM findings. Phase contrast images were also obtained to compare with both EVCM and IVCM findings. The change in cyst morphology with depth was evaluated by imaging the same cysts over a defined cornea depth measurement.

Results EVCM morphologies for live cysts included four main types—hyper-reflective central dot with hyper-reflective outer ring, hyper-reflective central dot with hyporeflective outer region, stellate shaped hyper-reflective centre with hyporeflective outer region and hyper-reflective round/polygonal shaped cyst; one main type for dead cysts—hyper-reflective central dot with hyporeflective outer region; two main types for empty cysts— hyper-reflective central dot with hyper-reflective outer ring/hyporeflective outer region; and one main type for trophozoites—large coarse speckled area of heterogeneous hyper-reflective material. Matching IVCM images show good correlation with EVCM. Cyst morphology altered when imaged at different depths.

Conclusion EVCM demonstrated the various forms of Acanthamoeba cyst and trophozoites can be used as a reference to identify similar structures on IVCM.

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  • Contributors All authors contributed equally to the work and the writing of the manuscript. All authors (NA, WH and SH) were involved in all aspects of article conception, writing, critical revision and review and approval. WH is the guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.