Your browser does not support JavaScript!

Home    Μελέτη στο μικροσκόπιο ατομικών δυνάμεων(ΜΑΔ) atomic force microscope (AFM)φυσιολογικού κερατοειδούς και κερατοειδούς μετά από φωτοδιαθλαστική κερατεκτομή με excimer laser  

Results - Details

Add to Basket
[Add to Basket]
Identifier uch.med.phd//2006lidataki
Title Μελέτη στο μικροσκόπιο ατομικών δυνάμεων(ΜΑΔ) atomic force microscope (AFM)φυσιολογικού κερατοειδούς και κερατοειδούς μετά από φωτοδιαθλαστική κερατεκτομή με excimer laser
Creator Lidataki, Stiliani
Abstract Cornea is the transparent avascular part of the anterior segment of the eye globe consisting of a stratified nonkeratinizing squamus epithelium, a stromal dense connective tissue, and an endothelium facing the anterior chamber. The cornea contributes largely to the intraocular refraction of the light. Because of its particular structural configuration, cornea is one of the classical subjects of microscopy research. Despite the fact that corneal surfaces were widely investigated, their appearance, as it was described until now especially after Scanning Electron Microscopic (EM) visualization, is not well defined. The published micrographs often show substantial differences that can be attributed to a lack of standardization and/or attention to preparative protocol. Atomic force microscope (AFM) is a scanning force microscope that depicts the three dimensional profile of a sample surface by scanning the surface with a sharp probe. Compared to other forms of microscopy used in the tissue study, having as criteria the resolution and the sample preparation, AFM offers several advantages. It can sometimes reach atomic resolution on hard flat surfaces Concerning the sample preparation AFM requires the minimal or no special preparation. The great advantage for histological studies is that AFM is able to image samples in aqueous environments thus permitting images to be obtained under near physiological conditions. Moreover it offers the possibility to study the dynamic of different processes as well as the nano-mechanical properties of relatively smooth surfaces. However, the use of the AFM is limited by different conditions as its scan size, scan speed and regarding especially biological samples the roughness and the chemical composition of the surface. In this study have been imaged the outer and the inner surfaces of fresh and fixed cornea (epithelium endothelium) and the corneal stroma, fixed, after mechanical or laser ablation. The fresh tissue observation although the imaging is difficult becomes challenging because it could reveal structures such as glycocalyx that cannot be preserved during the classical microscopy procedures. The difficulties of fresh tissue imaging have to do with the nature of its surface containing high-branched glycoaminoglycans in the glycocalyx and the imaging time that should be reduced to the minimum possible. The enzymatic treatment of endothelium surface facilitates the imaging by removing a part of the coating material and in the same time gives information for the constitution of this layer. The recorded images of the fixed epithelium and endothelium provided information comparable to the one already existing of different microscopic techniques especially of the Scanning Electron Microscory (SEM). In addition, in some samples nanoscale images reveal a very fine structure of a few nanometers on the surface. The imaging of the fixed corneal stroma after mechanical or laser ablation, provided information about the fine structrure of the collagen fibrils and of other extracellular matrix elements of the mechanically or laser ablated surfaces. Differences of the surface structure attributed to the effect of the laser radiation during the photorefractive keratectomy (PRK) with the excimer laser were discerned.
Issue date 2006-03-01
Date available 2006-09-29
Collection   School/Department--School of Medicine--Department of Medicine--Doctoral theses
  Type of Work--Doctoral theses
Views 247

Digital Documents
No preview available

Download document
View document
Views : 11