Characterization of elementary lesions of Fuchs endothelial corneal dystrophy and attempt at classification: analysis of 500 Descemet's membranes.

Abstract

Purpose : Fuchs' endothelial corneal dystrophy (FECD) is characterized by progressive changes in Descemet's membrane (DM). Its pathophysiology is only partially elucidated and involves certain genetic backgrounds, an abnormal response to oxidative stress, abnormal production of extracellular matrix and endothelial apoptosis. However, despite these similarities, there is heterogeneity in the clinical course. Objectives: To describe and characterize the different lesions of DM to determine whether there are subgroups of FECD

Methods : Study on operative residues, approved by an ethics committee. DMs of approximately 8 mm in diameter were obtained by Descemetorhexis from patients undergoing endothelial transplantation in one of 23 participating French and French-speaking centers (French Fuchs Study group). They were stored either in water to remove residual cells and allow analysis of the MD surface or fixed in 0.4% paraformaldehyde to allow analysis of residual cells. MDs were flat-mounted on glass slide, dehydrated, and then observed by brightfield and phase-contrast light microscopy with manual classification and image analysis.

Results : DM were procured from 500 patients (63% female) aged 71+/-11 years. 65% of the MD were in perfect condition, in one piece, allowing analysis of its entire surface without loss of information. Several elementary lesions were described: 1/ Guttae (constant) of different shapes, diameter, and with differences in organization (between central and peripheral areas but also from one patient to another), in particular radial alignments; 2/ fibrillar and curly structures (inconstant) more or less covering the most central Guttae; 3/ intra- or extracellular pigment (inconstant); 4/ other reliefs "imprinted" in the DM (constant); 5/ several populations of residual cells of normal or dystrophic appearance. Some associations were more frequent than others, allowing to define subgroups of FECD.

Conclusions : This unique and large collection allows, for the first time to our knowledge, to describe with great precision all lesions constituting DM at the stage when patients are transplanted in France. It highlights an unsuspected diversity of the histology of FECD. This first study will be followed by a prospective study to establish correlations between elementary lesions, possible subgroups, clinical characteristics and genetic background

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