| Glaucoma is the second blinding disease worldwide.The process of blindness is irreversible as usual.Glaucoma accounts for 8%of the blindness worldwide.The global prevalence of glaucoma is 3.54%among 40-80 year olds worldwide.Accordingly,it is estimated that more than 60 million people[11 suffer from glaucoma worldwide,and glaucoma is the leading cause of irreversible blindnes[2]and functional lower visionI3].In glaucoma,up to 20%of the patients showed the progression of degenerative visual field defects of retinal ganglion cells and optic nerve despite successful control of high intraocular pressure.On the other hand,many glaucomatous optic nerve and functional injuries under normal or even low intraocular pressure condition are still irreversible visual dysfunctionI4].In fact,elevated intraocular pressure is considered to be the least action that triggers the cascade reaction of optic nerve injury[5].The common features of all forms of glaucoma are progressive degeneration of optic nerve and loss of detectable retinal ganglion cell(RGC),structural and functional loss of trabecular reticulum,decrease of retinal nerve fiber layer thickness,thinning of nerve retinal edge of optic nerve disc and pale optic disc.[6].Age,race,high myopia,glaucoma cup and family history,hereditary metabolic diseases,excessive intraocular pressure and periocular circulation dysfiunction are high risk factors for glaucoma.[7]Many authors agree that the mechanical pressure is attributed to the sieve plate in the optic nerve papilla,which is the key site of axonal injury due to its anatomical structure and the particularity of adjacent tissues.[8]Mechanical constraints,ischemia,oxidative stress,and pressure difference across the sieve plate may affect the anterograde and retrograde axonal transport of the optic nerve,leading to the initiation and continuation of axonal degeneration of RGC.[9,10,11]A hypothesis indicates that impaired neurotrophic factor delivery will impair the survival of RGC,as a result of axonal transport blockade caused by increased IOP[10-14];However,glaucoma may have no abnormal intraocular pressure.In this case,the degeneration and degeneration of RGC were observed[15,16].For other patients,although they experienced high intraocular pressure,no changes in the structure and function of optic nerve fibers were observed[17]In fact,the elevated intraocular pressure is considered to be the smallest action that triggers cascade reactions leading to optic nerve injury.[5]Oxidative stress,hypoxia,cytotoxicity and exfoliation of nerve growth factor are involved in the apoptosis of retinal ganglion cells and optic nerve fiber.c[11,18-19]Essentially,the role of specific neurotrophic factors in the development and survival of RGC is widely accepted:c[11,14,20-23]such as brain-derived neurotrophic factor(BDNF)can promote the survival of RGC[24,22]nerve growth factor(NGF),glial cell-derived neurotrophic factor,insulin-like growth factor-1(IGF-1)leukemia inhibitor,[25]sinusoidal eye-related homeobox 6(SIX6)[26]Or OPTINEURIN(OPTN)gene[27]can delay the process of RGC death.Otherwise the POU domain,four transcription factors 1(POU4F1,called Brn3a)and three transcription factors(POU4F3,called Bm3c),Ebf helix-loop-helix transcription factor 3(Ebfl)and Onecut 1 and 2 are also participate in the differentiation and maturation of RGC cell sub-types.[28]The relationship between multifactors and optic ganglion cell apoptosis is a hot research topic from both life science research and clinic prevention strategy.So far,the pathogenesis of glaucomatous retinal ganglion cells and optic nerve damage remains uncertain.Since the appearance of mi-RNA in the field of life science in the late 1990s,it has been recognized as the most influential discovery in the 20th century.It plays an important role in many kinds of neurogenic tissues,and has been proved to be optic nerve and retinal photosensitive nerve transmission complex-optic ganglion cells in the main enrichment area of the eye.It has become a hot and complex point in the diagnosis and treatment of glaucoma to discover and identify pathogenic targets and clarify their regulatory mechanism at a more precise ultra micro-level of mi-RNA molecule. |
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