Review Article
Vitreous Substitutes: The Present and the Future
Table 1
Biochemical composition of the vitreous.
| Subgroups | Molecule | Action |
| Protein | Albumin (40%) | | Iron binding protein (30%) like transferrin | Protective effect to reduce iron toxicity | Collagens | Structure of the vitreous | Type II (60–70%) | | Type IX (25%) | | Type V/IX (10–25%) | | Type IV (<10%) | |
|
Glycosaminoglycan | Hyaluronic acid (66–115 microgram/mL concentration) | Determine the vitreous body viscosity | Chondroitin sulfate | Major component of extracellular matrix | Versican | | Type IX collagen | | Heparan sulfate | It maintains adequate spacing between the collagen fibrils |
| Metabolites | Glucose | To support the enzymatic activity | Lactic acid | | Ascorbic acid | Neovascularization inhibitor Increase proliferation of hyalocytes Potent antioxidant | Amino acids | Metabolic cells maintenance | Fatty acids unsaturated (50–55%) | Metabolic cells maintenance | Prostaglandins (100 picogram/mL) | Cells regulation | PGE2 | Cells regulation | PGF2alpha | Cells regulation | Prostacyclin | Cells regulation | Thromboxane | Cells regulation |
| Cells | Hyalocytes | Vitreous matrix creation and maintenance | Fibrocytes/fibroblasts | Vitreous matrix creation and maintenance | Macrophages | Cells and matrix regulation and degradation | Enzymes and metabolic activity: ACE | Cells regulation |
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