title: Corneal structure and transparency.
abstract: The corneal stroma plays several pivotal roles within the eye. Optically, it is the main refracting lens and thus has to combine almost perfect transmission of visible light with precise shape, in order to focus incoming light. Furthermore, mechanically it has to be extremely tough to protect the inner contents of the eye. These functions are governed by its structure at all hierarchical levels. The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought and that the intricacy of the arrangement of the collagenous lamellae provides the shape and the mechanical properties of the tissue. At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure. In this review we describe the current state of knowledge about the three-dimensional stromal architecture at the microscopic level, and about the control mechanisms at the nanoscopic level that lead to optical transparency.
authors.affiliation: Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK. Electronic address: meekkm@cf.ac.uk.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Meek
authors.affiliation: Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
authors.forename: Carlo
authors.initials: C
authors.lastname: Knupp
mesh_terms: D003094:Collagen / Q000032:analysis; D003315:Cornea / Q000502:physiology / Q000648:ultrastructure*; D003319:Corneal Stroma / Q000648:ultrastructure; D003459:Crystallins / Q000032:analysis; D016326:Extracellular Matrix Proteins / Q000032:analysis; D006801:Humans; D008854:Microscopy, Electron; D011509:Proteoglycans / Q000032:analysis
chemical_list: D003459:Crystallins; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D003094:Collagen
keywords: Collagen; Cornea; Structure; Theoretical modelling; Three-dimensional electron microscopy; Transparency; X-ray