Modern anatomical and physiological bases for maintaining the transparency of the corneal stroma

The article presents a literature review of the modern concept of anatomical and physiological structure and functioning of the cornea. The strict morphological structure and corneal tissue homeostasis ensure its transparency. Studying the mechanisms that regulate the constancy of the corneal tissue internal environment allows us to get closer to understanding the prospects forregenerative therapy for the corneal stroma pathology. The article discusses in detail the role and functional potential of corneal stromal cells, which are capable of reverse cytologic differentiation, which primarily ensures the maintenance of tissue homeostasis and corneal transparency. The functional activity of corneal cells can change for a number of reasons, which may be exogenous, iatrogenic (trauma, infection, etc.) or endogenous. Endogenous causes include: cell autoregulation pathologies (for example, enzyme defects); defects in transport systems leading to tissue hypoxia; disorders of the neuro-humoral regulation of trophism. The physical reason forthe violation of the corneal transparency is an increase in the light scattering. The article presents five main causes of increased light scattering in the opaque cornea, and also provides an overview of the main substances – components and products of cellular synthesis of corneal stromal cells: cytokines and growth factors (complex of the signal molecule and the SDF1/CXCR4 receptor, insulin-like growth factor 1, tumor necrosis factor alpha, intercellular adhesion molecule 1, erythropoietin, neurotrophic factors, etc.). Thus, corneal opacity can be caused by a single pathogenic mechanism or be the result of a complex effect of several factors. The main processes of tissue homeostasis regulation are aimed at maintaining the unique morphological structure of the cornea.

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