Table 4.

Different Collagen Types and Their Role in ERM

Collagen Type	Role
Collagen type I	Promotes the fibrotic process and contributes to the formation of the hard collagen scaffold, where the myofibroblast precursor cells, when anchored there, become more susceptible to fibrogenic factors [19]. Also, it affects the mechanical properties of ERM. Although it enhances adhesion to various tissues, recently formed collagens may influence the rigidity and digestibility of ERM. Important component of idiopathic ERM [18, 44].
Collagen type II	Proliferation and migration. It binds to cellular membrane receptors, while it has a significant role in matrix remodeling, fibrosis mediation and cell signaling. Important component of idiopathic ERM [18, 44].
Collagen type III	Promotes the fibrotic process and contributes to the formation of the hard collagen scaffold, where the myofibroblast precursor cells, when anchored there, become more susceptible to fibrogenic factors [19]. Also, it affects the mechanical properties of ERM. In addition to enhancing adhesion to various tissues, recently formed collagens may influence the rigidity and digestibility of ERM. Important component of idiopathic ERM [18, 44].
Collagen type IV	Promotes the fibrotic process and contributes to the formation of the hard collagen scaffold, where the myofibroblast precursor cells, when anchored there, become more susceptible to fibrogenic factors. Important component of idiopathic ERM [18, 19].
Collagen type V	Affects the mechanical properties of ERM. In addition to enhancing adhesion to various tissues, recently formed collagens may influence the rigidity and digestibility of ERM. Important component of idiopathic ERM [18, 44].
Collagen type VI	Contribution to the proliferation, migration and fibroblasts to myofibroblasts transdifferentiation, a vital procedure for mediating fibrosis, scar contraction and matrix remodeling, in many fibrotic diseases including ERM. It also forms a fine fibrillar network in idiopathic ERM. Important component of idiopathic ERM [18, 44, 83-85].

Abbreviations: ERM: epiretinal membrane