Characterization of Descemet membrane of Fuchs endothelial corneal dystrophy by chromatic confocal microscopy

Abstract

AbstractPurpose: Fuchs corneal endothelial dystrophy (FECD) causes chronic corneal edema and vision loss, and accounts for more than 50% of keratoplasty indications in occidental countries. The Descemet membrane (DM) gradually thickens because of extracellular matrix deposition and round excrescences named guttae accumulate. Chromatic confocal microscopy (CCM) is on optical device that analyses the nanotopography of surfaces.Aim: to study the feasibility of CCM technology to characterize guttae in FECD.Methods: Descemetorhexis of approximately 8 mm in diameter were obtained during endothelial grafts in 11 patients with FECD and control corneas were obtained from 3 donor corneas. The DM were fixed in 0.5% paraformaldehyde immediately after dissection. The CCM analysis was performed at room temperature on surfaces of 400 x 400 μm to characterize the DM with and without guttae. We measured positive and negative heights (peaks and valleys) relative to the mean altitude, as well as their distribution by asymmetry coefficient.Results: CCM resolution allowed to map nanotopography of the DM of FECD patients and controls. The surface of DM control was flat and homogeneous with maximum positive and negative heights of 1.07 ± 0.09 μm and 1.05 ± 0.07 μm, respectively. The height distribution was uniform with an asymmetry coefficient of 0.002 ± 0.23 μm, reflecting a Gaussian distribution (npeaks = nvalleys). The surface of FECD membranes was completely altered with a maximum peak of 6.05 ± 1.49 μm, up to 5.7 times higher than the control. The height distribution was disturbed with asymmetry value of 1.61 ± 0.79 μm (npeaks > nvalleys) and a maximum valley height (3.09 ± 0.79 μm) that was half that of the peak one.Conclusions: CCM is a promising technology to quantitatively characterize the 3D organization of the DM surface. CCM can be used to classify the different types of surface lesions of the FECD corneas and to follow evolution of DM alteration at different stages of the disease.