June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Confocal Microscopy for Diagnosis of Acanthamoeba Keratitis: Nidek versus Heidelberg
Author Affiliations & Notes
  • Jeffrey Ryan Golen
    F.I. Proctor Foundation, University of California, San Francisco, San Francisco, CA
  • Jeremy D Keenan
    F.I. Proctor Foundation, University of California, San Francisco, San Francisco, CA
  • Footnotes
    Commercial Relationships Jeffrey Golen, None; Jeremy Keenan, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 1614. doi:
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    • Get Citation

      Jeffrey Ryan Golen, Jeremy D Keenan; Confocal Microscopy for Diagnosis of Acanthamoeba Keratitis: Nidek versus Heidelberg. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1614.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To compare the diagnostic utility of the Nidek and Heidelberg systems for acanthamoeba keratitis.

 
Methods
 

The Nidek Confoscan4 and the Heidelberg HRT3 Rostock confocal microscopes were used in a consecutive series of patients suspected of having acanthamoeba keratitis. Images from both microscopes were presented in a random order to two masked graders. Examiners graded each series of images for the presence or absence of acanthamoeba cysts, and also documented whether their evaluation was made with a low or high degree of certainty. Graders discussed discrepancies and agreed on a single grade and level of certainty for all scans.

 
Results
 

18 total scans from 13 eyes were evaluated, including 5 eyes that were smear- or culture-positive and had examinations performed on both microscopes, and 8 control eyes that were smear-and/or and culture-negative, but exhibited suspicious keratitis clinically. Five control eyes were tested on the Nidek only and 3 control eyes were tested on the Heidelberg only. For the Heidelberg camera, all 5 smear- or culture-positive cases were correctly interpreted by expert examiners (sensitivity=100%, 95%CI 47.8 to 100%), and all 3 negative cases were correctly interpreted as negative (specificity=100%, 95%CI 29.2 to 100%). For the Nidek, 3 of 5 smear- or culture-positive cases were correctly identified by expert examiners as positive (sensitivity 60%, 95%CI 14.7 to 94.7%), and 5 out of 5 negative cases were correctly interpreted as negative (specificity=100%, 95%CI 47.8 to 100%). Of the five positive cases for each camera, 2 cases were identified as “high certainty” on each machine. There was no difference between the two microscopes among the 5 eyes that had both scans performed (P=0.50, McNemar’s test).

 
Conclusions
 

Both the Nidek and Heidelberg confocal microscopes are useful in diagnosis of acanthamoeba keratitis. Although not statistically significant in this small study, the Heidelberg microscope appeared to be more effective in identifying acanthamoeba cysts than the Nidek. Neither microscope produced false positive tests. These results could be dependent on the graders from this specific study and should be confirmed in future studies.  

 
Figure 1a: Acanthamoeba cysts seen on Nidek Confoscan4
 
Figure 1a: Acanthamoeba cysts seen on Nidek Confoscan4
 
 
Figure 1b: The same eye, showing acanthamoeba cysts seen with the Heidelberg HRT3 Rostock confocal microscope
 
Figure 1b: The same eye, showing acanthamoeba cysts seen with the Heidelberg HRT3 Rostock confocal microscope

 
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