[Atomic force microscopy in the study of retinal structure]

Layer-by-Layer Investigation of Ultrastructures and Biomechanics of Human Cornea

The cornea is an avascular, innervated, and transparent tissue composed of five layers: the epithelium, Bowman’s layer, stroma, Descemet’s membrane, and endothelium. It is located in the outermost fraction of the eyeball and is responsible for the refraction of two-thirds of light and protection from external mechanical damage. Although several studies have been done on the cornea on the macroscopic scale, there is a lack of studies on the micro-nanoscopic scale, especially an analysis evaluating the cornea layer by layer. In this study, atomic force microscopy (AFM) was employed to assess four layers that form the cornea, analyzing: adhesion, stiffness, and roughness. The results showed microvilli in the epithelial and endothelial layers, pores in the basement membrane, and collagen fibers in the Stroma. These data increase the knowledge about the human cornea layers’ ultrastructures and adds new information about its biophysical properties.

[Experimental studies of the biomechanical properties of the cornea]

The review presents the results of experimental studies of the biomechanical properties of the cornea. Selective evaluation of the individual corneal structures (for example, limiting membranes) using classical mechanical tests is to a certain extent limited due to the rather small thickness of these structures and the related difficulties in sample fixation. In real practice, the use of a method better adapted for conducting such studies - atomic force microscopy (AFM) - remains promising, since on the one hand it eliminates the need for mechanical capture and retention of the sample, and on the other - provides the capability for studying its segments separately.

[Pharmacological and physiotherapeutic methods of treating non-exudative age-related macular degeneration]

The non-exudative form of age-related macular degeneration (AMD) is a disease with long-term progression for which effective treatments have not been found. Many studies are being conducted to find effective drugs to prevent the appearance of drusen and increase in RPE atrophy area, which could help avoid this more dangerous form of AMD. The main drugs (nutraceuticals) that are used to treat the dry form of AMD are lutein, zeaxanthin and omega-3 fatty acids. Additionally, treatment may include nanosecond laser therapy for drusen in advanced AMD, panretinal subthreshold micropulse laser exposure for atrophic AMD, as well as microcurrent stimulation. Further research in this area should be aimed at understanding all the pathogenetic mechanisms associated with the development of AMD, and developing new approaches to the treatment of this disease including physiotherapy.