Descemet Membrane Thickening as a Sign for the Diagnosis of Corneal Graft Rejection: An Ex Vivo Study

Abstract

Purpose To disclose, using an ex vivo study, the histopathological mechanism behind the in vivo thickening of the Endothelium/Descemet’s membrane complex (En/DM) observed in rejected corneal grafts (RCGs). Methods Descemet’s membrane (DM), endothelium (En), and retrocorneal membranes (RCM) make up the total En/DM thickness. These layers are non-differentiable by HD-OCT; therefore, the source of the thickening is unclear from an in vivo perspective. A retrospective ex vivo study (from September 2015 to December 2015) was conducted to measure the thicknesses of DM, En, and RCM in 54 corneal specimens (31 RCGs and 23 controls) using light microscopy. Controls were globes with posterior melanoma without corneal involvement. Results There were 54 corneas examined ex vivo with mean age 58.1 ± 12.2 in controls and 51.7 ± 27.9 years in rejected corneal grafts. The ex vivo study uncovered the histopathological mechanism of En/DM thickening to be secondary to significant thickening (p<0.001) of DM (6.5 ± 2.4 μm) in rejected corneal grafts compared to controls (3.9 ± 1.5 μm). Conclusions Our ex vivo study shows Descemet’s membrane is responsible for the thickening of the En/DM in RCGs observed in vivo by HD-OCT and not the endothelium or retrocorneal membrane.

Automatic Segmentation of Corneal Microlayers on Optical Coherence Tomography Images

“…There is a strong evidence in the literature that measuring the thicknesses of corneal microlayers in vivo is valuable for the diagnosis of numerous corneal diseases, such as Fuchs dystrophy, keratoconus, and corneal graft rejection 4,5,12–15. Those studies have shown excellent potential in the diagnosis of these pathologies using thickness of corneal microlayers, but they have also disclosed limitations in the technology.…”

“…There are six interfaces between the corneal microlayers, namely, the air-epithelium interface (EP), the basal-epithelial interface (BS), the epithelium-Bowman's interface (BW), the Bowman's-stroma interface (ST), the DM, and the endothelium-aqueous interface (EN). Measuring the thicknesses of those microlayers in vivo has proven to be valuable for the diagnosis of various corneal diseases, such as Fuchs dystrophy, keratoconus, corneal graft rejection, and dry eye 4,5,12–15. For example, thinning of Bowman's microlayer has been shown to be an accurate sign for the diagnosis of keratoconus 4,16.…”

Corneal Microlayer Optical Tomography Review

“…OCT assessment of the tear meniscus has been extensively studied during the last 10 years [32]. The pathophysiology of dry eye disease is characterized by instability of the pre-corneal tear film along with increased osmolarity and ocular surface inflammation and damage [33].…”

“…OCT meniscometry solves this problem by continuously measuring the tear film, using a tear meniscus to represent the total volume. This method of acquiring images is objective, non-invasive and rapid [32,34]. However, data analysis is complex, operator-dependent and time-consuming [36].…”

“…However, data analysis is complex, operator-dependent and time-consuming [36]. Tear meniscus height, curvature, and cross-sectional area are widely used in clinical practice and demonstrate good diagnostic performance and correlations with other tests [32,34].…”