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

Financial Disclosures None of the authors have any financial disclosures

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 diseased 4 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 Mar-Apr; 217(2): Modis L Jr et al, Corneal endothelial cell density and pachymetry measured by contact and noncontact specular microscopy. J Cataract Refract Surg Oct;28(10): Doughty MJ et al, Toward a quantitative analysis of corneal endothelial cell morphology: a review of techniques and their application. Optom Vis Sci Sep; 66(9): NAVIS for Confoscan 4 Operator’s Manual ( )

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

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/mm 2 ] Difference between two methods of >250 cells/mm 2 was considered clinically significant INCLUSION CRITERIA

Automated: 2613 cell/mm 2 Manual mode: 2578 cell/mm 2 Normal cornea

Automated: 1675cell/mm 2 Manual mode: 1503 cell/mm 2 Grade 2 Fuchs’ Manual mode: 423 cell/mm 2 Automated: 1776 cell/mm 2 Advanced Fuchs’

RESULTS Table 1. Endothelial cell counts (cells/mm 2 ) in healthy and Fuchs' dystrophy cornea Images Average auto count Average manual count Average difference Range of cells(differen ce) p value Healthy cornea ± ± ± to 402 cells Fuchs' Dystroph y ± ± ± to 1631 cells <0.0001

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 / mm ± ± ± to 402 cells < Cell count less than 1000 cells / mm ± ± ± to1631 cells <0.0001

Advantage of automated mode is that there is no inter-observer variability, it is faster, repetitive and is independent of users’ experience and skills 5 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/mm 2 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 Jun; 239(5):

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

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