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Jay McLaren, Lori Bachman, Sanjay Patel; Objective Assessment of the Corneal Endothelium in Fuchs Endothelial Dystrophy. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1673.
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© ARVO (1962-2015); The Authors (2016-present)
Assessment of the corneal endothelium in early stages of Fuchs endothelial dystrophy is subject to sampling errors because of the non-uniform distribution of guttae. In this study we developed a standardized method of endothelial assessment and examined the predictive relationship between the effective endothelial cell density (ECD) and severity of Fuchs dystrophy based on subjective grades. We also examined the relationship between effective ECD and anterior corneal structural changes (backscattered light).
The corneal endothelium of 51 eyes from 30 patients, with varying degrees of Fuchs endothelial dystrophy, was examined by using confocal microscopy (ConfoScan 4, Nidek Technologies) with a 20x non-contact objective. In 2 to 3 images that sampled the central endothelium, local contiguous cell density was determined by using a variable frame method (2 to 177 cells in 1 to 10 patches, depending on the distribution of guttae). The effective ECD was the product of the local cell density and the ratio of the sample area not covered by guttae to total sample area, which was determined by image analysis. The severity of the disease in each eye was assessed during slit-lamp examination by two examiners based on a modified Krachmer grade (1-6). In 55 eyes with Fuchs dystrophy from a second group of 30 patients, the clinical grade was predicted from the effective ECD and the regression coefficients from the first group, and compared to the subjective clinical grade assigned by one examiner. The relationship between effective ECD and backscatter from the anterior stroma, based on brightness of confocal images (40x objective, ConfoScan 4) in the second group, was examined by Pearson regression. Significance was determined by using generalized estimating equation models.
The effective ECD decreased linearly with subjective grade (r=-0.93, p<0.001). The grade predicted from the effective ECD differed from the subjective clinical grade by -0.1 ± 0.8 grade (mean ± SD). Mean backscatter from the anterior stroma was inversely correlated with the effective ECD (r=-0.59, p<0.001).
The effective ECD in confocal images provides an objective means of assessing severity of Fuchs dystrophy and correlates with structural changes in the anterior stroma. It is sensitive to changes in early stages of the disease, before clinical edema appears, and might be a useful tool in clinical studies.
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