Endothelial cell size comparison in different areas of corneas affected by Fuchs’s Endothelial Dystrophy (FED)

Abstract

Purpose : The endothelial structure that characterizes FED is Descemet's membrane excrescences (DME). Horizontal areas of the cornea seems to have a worse Endothelial Mosaic (EM) profile that the vertical areas; The most severe affected areas are the central and temporal areas of the cornea and the most preserved is superior area of the cornea. At the Figure 1 is possible to identity a severity scoring system for FED, recommended by the authors and colls, to classify the involvement of the different areas of the EM. The Specular Microscopy (SM) estimate the amount of corneal endothelial cells (CEC) reporting the amount of these cells in the standard EM surface of 1mm². EM of FED has areas with different degrees of involvement by DME, which make it impossible to calculate endothelial cell density (ECD), since DME occupy a space in which CEC is not identified. Considering the irregular profile in the distribution of the DME, this study aims to identify differences in the size CEC between different areas of the EM with different degrees of involvement in the FED.

Methods : A cross-sectional study involving 98 eyes of 49 patients with the clinical diagnosis of FED was performed at the Clinica de Olhos Dr. Fernando Abib (Curitiba, Brazil). Contact Corneal Specular Microscope (BioOptics, USA) was used to score the severity of FED based on EM profile (Figure 1) and calculate the CEC area. Null Hypothesis: CEC area does not differ in the areas of the EM affected by DME; Alternative Hypothesis: CEC area is larger in areas of the EM affected by DME. Comparison 1: CEC Area at EM grade 0-1 X grade 2-3; Comparison 2: CEC Area at EM grade 0-1 X grade 4-5. Descriptive statistic was used to describe CEC and one tailed t-test for 2 independent means with level of significance of 0.05.

Results : Comparison 1 - CEC Area at EM grade 0-1 X grade 2-3: The t-value is -1.72445. The p-value is 0.042755. The result is significant at p < .05. Comparison 2 - CEC Area at EM grade 0-1 X grade 4-5: The t-value is -3.50202. The p-value is 0.000266. The result is significant at p < .05.

Conclusions : In DEF patients, the most affected areas by EMD present larger CEC among the outgrowth than in the unaffected areas. This suggests that in areas with lower amounts of CEC due to the presence of EMDs, the CEC that exist between these EMDs still exist in smaller amounts because they are larger.

This is a 2020 ARVO Annual Meeting abstract.