elastin and Keratoconus

The pre-Descemet's layer/Dua's layer, also termed the Dua-Fine layer and the pre-posterior limiting lamina layer, lies anterior to the Descemet's membrane in the cornea, is 10 μm (range 6-16) thick, made predominantly of type I and some type VI collagen with abundant elastin, more than any other layer of the cornea. It has high tensile strength (bursting pressure up to 700 mm of Hg), is impervious to air and almost acellular. At the periphery it demonstrates fenestrations and ramifies to become the core of the trabecular meshwork, with implications for intraocular pressure and glaucoma. It has been demonstrated in some species of animals. The layer has assumed considerable importance in anterior and posterior lamellar corneal transplant surgery by improving our understanding of the behaviour of corneal tissue during these procedures, improved techniques and made the surgery safer with better outcomes. It has led to the innovation of new surgical procedures namely, pre-Descemet's endothelial keratoplasty, suture management of acute hydrops, DALK-triple and Fogla's mini DALK. The discovery and knowledge of the layer has introduced paradigm shifts in our age old concepts of Descemet's membrane detachment, acute corneal hydrops in keratoconus and Descemetoceles, with impact on management approaches. It has been shown to contribute to the pathology and clinical signs observed in corneal infections and some corneal dystrophies. Early evidence suggests that it may have a role in the pathogenesis of keratoconus in relation to its elastin content. Its contribution to corneal biomechanics and glaucoma are subjects of current investigations.

Topics: Corneal Transplantation; Descemet Membrane; Edema; Elastin; Glaucoma; Humans; Keratoconus

Williams-Beuren syndrome is a multisystemic genetic disorder caused by a contiguous gene deletion at 7q11.23. Keratoconus is a complex disease and it is suspected to have a genetic origin, although the specific gene responsible for keratoconus has not been identified. Although there are several ocular features in Williams-Beuren syndrome, keratoconus is not regularly described as part of this syndrome.. To report a new patient with keratoconus and Williams-Beuren syndrome.. This is the third case of an association between Williams-Beuren syndrome and keratoconus. The authors believe that the Williams-Beuren syndrome chromosome region can be a possible target for further investigation as the genetic basis of keratoconus.

Topics: Adult; Chromosomes, Human, Pair 7; Corneal Topography; Elastin; Exons; Gene Deletion; Humans; Keratoconus; Lim Kinases; Male; Real-Time Polymerase Chain Reaction; Williams Syndrome

To report two memorable clinical comorbid cases of Williams-Beuren syndrome (WBS) associated with keratoconus (KC). WBS is known to be an abnormal systemic development caused by a microdeletion of contiguous genes in chromosome 7q11.23, which includes the elastin gene. KC is currently suspected to have a genetic origin but the responsible gene has not been clearly identified.. KC and WBS is described for two cases. Risk factors for KC were investigated by interviewing parents, and WBS was confirmed by fluorescence in-situ hybridization (FISH). Histological analysis with Orcein (coloring specific to elastin) on the receiver corneal button of patient 1 was carried out.. Because of the rarity of both pathologies and the absence of other risk factors for developing keratoconus, we considered a possible genetic link. The association had never been reported in the literature. The first histological investigation could not confirm the presence of abnormal elastin in the cornea, but another gene could be responsible.. This report highlights the first cases of this association. Further histological and cytogenetic investigation on the deletion should be interesting in order to argue a possible physiopathological or genomic link.

Topics: Adult; Chromosomes, Human, Pair 7; Cornea; Corneal Topography; Elastin; Female; Humans; In Situ Hybridization, Fluorescence; Keratoconus; Male; Risk Factors; Visual Acuity; Williams Syndrome; Young Adult