Ultrastructural 3D imaging of collagen fibrils and proteoglycans of macular dystrophy cornea

Abstract

AbstractPurpose Macular cornea dystrophy (MCD) is an autosomal, recessive, genetic disorder, involving a gene on chromosome 6 that leads to aberrant keratan sulphate synthesis. Here we report ultrastructural 3D image analysis of collagen fibrils (CF) and proteoglycans (PGs) macular corneal dystrophy (MCD) corneas.Methods Three normal and three macular dystrophy (MCD) corneas were used for the study. The corneas were fixed in the 2.5% glutaraldehyde containing cuprolinic blue and processed for electron microscopy. 120 images were taken and used to construct 3D images of CF and PGs.Results 3D image analysis showed that the PGs were embedded within the collagen fibrils of the stroma. There were less electron dense particles within the CF of the MCD cornea compared to within the normal CF. The diameter of the CF in the anterior stroma was larger compared to the CF diameter in the posterior stroma. The PGs area in the anterior stroma was significantly larger compared to the PGs area in the middle and posterior stroma. The PGs around the degenerated keratocytes were much larger. PGs areas in the MCD cornea were significantly larger than the PGs areas of the normal cornea.Conclusion Ultrastructural 3D imaging provides detailed ultrastructural features of CF and PGs. A large aggregation of the PGs in the anterior stroma suggests that the degeneration of the anterior stroma was more severe compared to the degeneration of the middle and posterior stroma.