Nadezhda V Khamnagdaeva
Pirogov Russian National Research Medical University, Moscow, Russia
Title: Disorders of retinol metabolism in the conceptual field of development of adaptive myopia
Biography
Biography: Nadezhda V Khamnagdaeva
Abstract
Purpose: To study the ultrastructural features of the sclera in the simulation of axial myopia in the experiment and the reaction of scleral fibroblasts to various concentrations of all-trans retinoic acid.
Methods: 15 experimental 2 month old animal with weight 2,0-2,5 kilogram took a part in our study. To stimulate myopia, into the left internal carotid artery of every animal, catheter (Vasofix Certo 24G) was installed. Within 6 months, 0.5 ml of trans retinoic acid was administered daily at a concentration of 0.06 mg/ml (Sigma-Aldrich, USA) [5]. Clinical refraction was evaluated and echobiometric studies were performed. Transmission electron microscopy was used for morphological studies of scleral samples. Determination of the sensitivity of fibroblasts to retinoic acid was assessed using a microtetrazolium test (MTT test).
Results: The formation of axial myopia is closely related to scleral remodeling. Trans-retinoic acid is a factor that affects on proliferative activity of fibroblasts, hypertrophy and hyperplasia of cells, an increase in the volume of an extracellular matrix, thinning of collagen and elastic fibers.
Conclusion: A model for the formation of axial myopia in which the main initiating factor of pathogenesis is a violation of the process of physiological regeneration of photoreceptor disks is proposed. The slow absorption of retinal pigment epithelium by the cells of distal fragments of photoreceptor disks leads to the activation of oxidative processes (the concentration of vitamin A decreases and the concentration of trans retinoic acid increases). Activation of lipid peroxidation has a damaging effect on cells of the vascular endothelium, the photoreceptor layer of the retina, scleral fibroblasts. Remodeling of the sclera develops with the background of a weakened transfer of necessary metabolites through the damaged endothelium and causes the synthesis of a fragile V type of collagen with short chains.