Abstract
Purpose: :
Corneal endothelial cell imaging is one of the main clinical parameters used to evaluate patients with Fuchs endothelial corneal dystrophy (FECD). Corneal guttae have been described as major risk factors for endothelial cell loss and FECD progression. The purpose of this study was to compare endothelial cell density (ECD) using specular and confocal microscopies and to analyze regional variability of ECD between guttate and non-guttate areas of patients with FECD.
Methods: :
Specular microscopy (Konan Specular Microscope) and confocal microscopy (HRT3/Rostock Cornea Module) was performed on 26 patients with FECD (10 males; average age 64 +/- 13 years). Noncontact specular microscopy images were taken and the proprietary software was used to calculate central corneal thickness (CCT), ECD, coefficient of variability (CV), and percentage of hexagonal cells. Contact HRT3 images were taken by selecting the sharpest focus of the endothelial cell layer and recording the image depth. Endothelial cell counts were performed in 2 central areas of equal size: one area including ≥1 guttae and one area devoid of guttae. Cell counts were performed manually, and the proprietary software analysis was used to calculate ECD.
Results: :
Out of 49 eyes, only seven eyes of 5 patients had high quality specular and HRT3 imaging performed on the same eye. In these eyes, the average CCT by specular was 602 +/- 62 microns and 591 +/- 74 microns by HRT3 (p = 0.95). The average ECD was 2010 +/- 469 by specular and 2054 +/- 551 by HRT3 (p = 0.89). In patients with good quality specular imaging, CV was 48 +/- 24 and the percentage of hexagonal cells was 44 +/- 15. Out of 26 patients (49 eyes) that had HRT3 performed, 22 patients (39 eyes) had sufficient image quality to assess guttate and non-guttate areas. The average ECD was 2171 +/- 713 in areas without guttae and 1203 +/- 660 in areas surrounding guttae by HRT3. The ECD was decreased by 43 +/- 24 % in the areas surrounding guttae compared to the areas without guttae (n=39, p<0.001).
Conclusions: :
In early FECD, both imaging modalites can be used to reliably determine ECD and CCT. In the later stages of FECD, specular microscopy cannot capture endothelial cell mosaic, while HRT3 is able to image both guttate and non-guttate regions and provide an ECD for both areas. There is a significant decrease in ECD around guttae compared to non-guttate areas, indicating marked regional variability in the endothelial cell loss of FECD patients.
Keywords: cornea: endothelium • imaging/image analysis: clinical • apoptosis/cell death