Correlation of clinical fibrillar layer detection with corneal thickness in advanced Fuchs endothelial corneal dystrophy eyes.

Abstract

Purpose : Central geographic subendothelial deposits in the form of a fibrillar layer (FL) are formed in advanced stages of Fuchs endothelial corneal dystrophy (FECD). Previous studies demonstrated a decrease in corneal endothelial cell (CEC) density and an increase in corneal backscatter in the FL area. The present study investigated the association of clinical FL detection with alterations in corneal thickness.

Methods : Analysis of patients (n=96) presenting for Descemet membrane endothelial keratoplasty (DMEK) for advanced FECD at the Department of Ophthalmology, University Hospital of Cologne, Germany. Slit lamp biomicroscopy with FECD grading was followed by Scheimpflug imaging with en face backscatter analysis and tomography / pachymetric analysis. FL dimensions were measured and correlation with tomographic / pachymetric values was performed. Formal approval to conduct this study was obtained from the Ethics Committee of the University of Cologne (No. 16.424). The research adhered to tenets of the Declaration of Helsinki.

Results : A FL was detected in 74% of all eyes (n=71). FL dimension measures (mean + SD) were for area 9.97+-5.13 mm², for maximum caliper diameter 4.38+-1.07 mm, for maximum vertical caliper diameter 3.50+-0.93 mm, and for maximum horizontal caliper diameter 4.09+-1.10 mm. Pachymetric values in FL-positive versus FL-negative eyes were for central corneal thickness (CCT) 614.59+-51.82 µm and 575.12+-48.38 µm (p=0.001), for corneal thickness at the apex (ACT) 613.97+-51.57 µm and 575.20+-46.15 µm, for peripheral corneal thickness at 1mm (PCT_1mm) 615,73+-49,95 µm and 580,20+-44.21 µm (p=0.002), for PCT_2mm 625.15+-47.63 µm and 599.07+-40.85 µm (p=0.017), for PCT_3mm 651.04+-46.32 µm and 635.04+-39.86 µm (p=0.128) and for PCT_4mm 695.07+-51.75 µm and 686.00+-43.20 µm (p=0.435), respectively. Correlation analysis indicated a weak correlation for the FL maximum vertical caliper diameter with ACT and PCT_1mm values.

Conclusions : Scheimpflug en face backscatter detection of a FL is associated with increased corneal thickness within the central 2 mm of advanced FECD eyes. Combined with our previous studies showing reduced CEC count and increased light scattering in the FL area this provides further evidence that the detection of a FL may qualify as a criterion for intervention in FECD patients in the future.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.