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Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy , Debarun Dutta, Varsha M Rathi Cornea and Anterior Segment Services, L V Prasad Eye Institute, Hyderabad, India Poster ID: 1685

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Page 1: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in

Fuchs' Endothelial Dystrophy

Somasheila I Murthy, Debarun Dutta, Varsha M Rathi

Cornea and Anterior Segment Services, L V Prasad Eye Institute, Hyderabad, India

Poster ID: 16856

Page 2: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

Financial Disclosures

None of the authors have any financial

disclosures

Page 3: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

• Endothelial cells are critical to maintain corneal transparency and its count is an indicator of endothelial health or disease 1, 2, 3

• The cell count software of NIDEK Confoscan 4 is regularly used to perform corneal endothelial cell analysis, either automatically or manually

• Accuracy of automated analysis falls as the cornea is more and more diseased4

• Manual count is recommended, however this is time consuming

BACKGROUND

1. Klias et al , Comparison of endothelial cell count using confocal and contact specular microscopy. Ophthalmologica. 2003 Mar-Apr; 217(2):99-103.

2. Modis L Jr et al , Corneal endothelial cell density and pachymetry measured by contact and noncontact specular microscopy. J Cataract Refract Surg. 2002 Oct;28(10):1763-9.

3. Doughty MJ et al, Toward a quantitative analysis of corneal endothelial cell morphology: a review of techniques and their application. Optom Vis Sci. 1989 Sep; 66(9):626-42.

4. 4. NAVIS for Confoscan 4 Operator’s Manual (2005-2007)

Page 4: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

Hypothesis: There is a cut-off at which automated count is accurate and reliable

Purpose: To evaluate the difference in endothelial cell count between automated and manual methods in healthy corneas and in Fuchs’ endothelial dystrophy

Methods: • Retrospective observational study• Data was analysed by single experienced observer• One hundred images from both healthy and Fuchs’

endothelial dystrophy were selected for the study• Archived images from the NIDEK Confoscan 4 were

used to procure endothelial cell counts by automated and manual methods

PURPOSE, METHODS

Page 5: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

The following parameters were required to select the image:

• Endothelial images: clear on all slides • At least 50 cells were taken in each in slide• After having selected the Region of Interest, the

automatic cell count was processed• For manual count, cells were selected in the region

of interest. Density information was calculated as: Density = cells in polygon / Polygon area [cells/mm2]

• Difference between two methods of >250 cells/mm2 was considered clinically significant

INCLUSION CRITERIA

Page 6: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

Automated: 2613 cell/mm2Manual mode: 2578 cell/mm2

Normal cornea

Page 7: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

Automated: 1675cell/mm2Manual mode: 1503 cell/mm2

Grade 2 Fuchs’

Manual mode: 423 cell/mm2 Automated: 1776 cell/mm2

Advanced Fuchs’

Page 8: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

RESULTS

Table 1. Endothelial cell counts (cells/mm2) in healthy and Fuchs' dystrophy cornea

Images Average

auto count

Average

manual count

Average

difference

Range of

cells(differen

ce)

p value

Healthy

cornea

100 2471.24 ±

273.19

2444.50 ±

370.30

125.67 ±

86.9

2 to 402 cells 0.0463

Fuchs'

Dystroph

y

100 1827.73 ±

334.31

1196.71 ±

637.29

633.04 ±

435.03

54 to 1631

cells

<0.0001

Page 9: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

RESULTS

Table 2. Endothelial cell counts done by automated and manual methods in images from Fuchs'

dystrophy

  Number

of Images

Average

auto count

Average

manual count

Average

difference

Range of

cells

(difference)

p value

Cell count more

than 1000 cells /

mm2

49 2028.73 ±

329.53

1719.82 ±

489.47

312.96 ±

337.27

2 to 402

cells

<0.0001

Cell count less

than 1000 cells /

mm2

51 1626.73 ±

186.50

673.62 ±

149.52

953.12 ±

246.70

54 to1631

cells

<0.0001

Page 10: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

• Advantage of automated mode is that there is no inter-observer variability, it is faster, repetitive and is independent of users’ experience and skills5

• In the other hand manual mode is time consuming needs higher level of technical skills and thereof it is unsuitable in busy clinic

• In our study the results have shown a large variability between the two methods (as much as up to more than 900 cells/mm2 difference) in advanced cases of Fuchs’ dystrophy.

Discussion

5. Imre L et al, Reliability and reproducibility of corneal endothelial image analysis by in vivo confocal microscopy. Graefes Arch Clin Exp Ophthalmol. 2001 Jun; 239(5):356-60.

Page 11: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

• Decision on surgery in Fuchs’ often is aided by the cell count.

• Performing the test in automated mode would overestimate the count, thus delaying the surgical intervention and perhaps final outcome

• Both the clinician and investigator need to be aware

• More advanced diseased corneas should undergo manual count

Discussion

Page 12: Comparison of Endothelial Cell Count by Manual and Automated Methods in Normal Corneas and in Fuchs' Endothelial Dystrophy Somasheila I Murthy, Debarun

• In healthy corneas, any method can be used• Diseased corneas: the accuracy of the automated

count decreased with decrease in total cells• Manual count is therefore more reliable in

compromised endothelium • Automated count overestimates the results, and

can even give a value in normal range, thus misleading the clinician

Conclusion