Age-related changes of the vitreous body

Abstract

Innovative advances in recent years in the study of pathological changes of the posterior segment of the eye including the use of optical coherence tomography which is considered the gold standard for diagnosing vitreoretinal interface pathology, not only significantly expanded the idea of the most prevalent lesions of the structure of posterior eye segment but also discovered absolutely new aspects of their pathology. The review emphasizes the spreading understanding of vitreous body, its age-related changes in the pathology of the posterior eye segment. Two main interrelated processes occurring in the vitreous body — synchysis and syneresis, gradually increasing with age, are considered. Synchysis process begins at the early age and by the age of 70 reaches 50% of the volume of the vitreous body in 70% of the population. Parallelly, syneresis provides strength and plasticity of the entire vitreous volume due to collagen involved in formation of fibrillar frame. An important role in maintaining a stable and viscoelastic structure of the vitreous body, belonging to hyaluronic acid, is discussed, the level of which remains relatively stable at any age due to its constant synthesis. The accumulated data on the structure of age-related and pathological biodegradation of the vitreous body demonstrates inevitable progression of this process leading to age-related posterior vitreous detachment, which is a detachment of the posterior cortical layers of the vitreous body from subjacent retina. Posterior detachment under the influence of age-related changes in the vitreous body has certain stages — from incomplete juxtafoveolar detachment to complete posterior vitreous detachment with clinical retinal changes corresponding to each stage (idiopathic macular holes, lamellar macular tears, macular fibrosis, vitreomacular traction syndrome, myopic foveoschisis). Complete posterior vitreous detachment usually does not cause anatomical retinal disorders and any clinical forms of its diseases, thus, it can be considered as a natural favorable outcome.