Stem cell transplantation for optic neuropathy 1.What is called optic nerve hypoplasia? What are the causes of optic nerve hypoplasia? Optic Nerve Hypoplasia (ONH) is the most common congenital abnormality of the optic disc. It is caused by the impaired differentiation of the retinal ganglion cell layer during 13-17 mm embryonic development for some unknown reason. It is one of the important causes of low vision in children. Etiology of optic nerve hypoplasia: The etiology of optic nerve hypoplasia is unknown. From the analysis of literature, optic nerve hypoplasia is associated with a variety of factors, a few of which are dominantly inherited and most of which may be related to maternal exposure to drugs or infectious diseases in early pregnancy, such as phenytoin sodium, quinine, lysergic acid, cocaine, alcohol, etc.; the latter, such as cytomegalovirus, syphilis, rubella, etc. Mothers with insulin-dependent diabetes mellitus, fetal alcoholism syndrome, etc. are associated, and posterior uterine tilt can produce optic disc lesions (homozygous biased dysplasia), presumably caused by transsynaptic transmission degeneration. The increase in alcohol and drug abuse abroad has also led to a significant increase in optic nerve hypoplasia. Optic nerve hypoplasia symptoms: The optic disc is small and gray, and may be surrounded by a mixed-colored outer halo, forming a double ring sign. There are abnormalities in the visual field of vision. It may be associated with microphthalmia, nystagmus, and iris choroidal defect. There may be endocrine and central nervous system abnormalities throughout the body. Foreign reports: vision in the affected eye varies from normal to loss of vision. The involvement is usually bilateral. In China, patients with optic nerve hypoplasia have a high degree of visual impairment at birth, mostly unilateral, but also bilateral. Bilateral cases often have a genetic history. Other ocular signs: optic nerve hypoplasia may be associated with microphthalmia, nystagmus, iris choroidal defects, lid adhesions, narrow tear dots, strabismus, ptosis, and wide spacing between the eyes. Optic nerve hypoplasia may not be associated with other ocular abnormalities, except for astigmatism, which is usually associated with it. A masking test should be performed if there is a suspicion that the patient also has varying degrees of amblyopia. Systemic symptoms: Optic nerve hypoplasia is often associated with many central nervous system and endocrine disorders. Some patients have growth hormone, thyroxine, and adrenocorticotropic hormone deficiencies or insufficiencies, such as: growth retardation, short stature, cerebral hypoplasia, tachyphylaxis, epilepsy, enuresis, hypothyroidism, hypoadrenocorticism, and hyperprolactinemia. Endocrine hypoplasia progresses gradually and repeated evaluation is necessary. 2.What is the conventional treatment for optic nerve hypoplasia? Optic nerve hypoplasia is a congenital developmental abnormality and there is no specific treatment. If growth hormone deficiency is present, growth hormone therapy can be applied. In cases of optic nerve hypoplasia with partial vision and strabismus, some people advocate the use of healthy eye masking method to promote the function of macular central sulcus optic cells and prevent further degeneration due to loss of use. Brodsky et al. reported sudden death due to fever and dehydration in patients with adrenocorticotropic hormone deficiency, uveitis and thermoregulatory disorders, in which the key factor in the pathogenesis was forebrain hypoplasia, and the growth hormone deficiency and uveitis accompanying the disease could be corrected clinically. The growth hormone deficiency and uropathy associated with this disease can be corrected clinically, and patients can recover normal bone growth. 3.Why can stem cells treat retinal degeneration? In some retinal diseases, the death of photoreceptor cells is caused by congenital malformations and/or destruction or death of supporting cells in the retinal pigment epithelium. And certain other parts of the body can handle similar cell death. This is because other cells present in the tissues are able to divide to create new cells to replenish existing cells by way of regulation. Unfortunately, mature retinal photoreceptor cells do not have this ability. This is why stem cells may be very useful, as some of them have the ability to divide and form new photoreceptors. Therefore, it is hoped that they can be used to replenish photoreceptors in diseased retinas in the future. 4.How can stem cells treat retinal diseases? Stem cells can be surgically transplanted into the eye or drugs can be developed to activate appropriate populations of stem cells that naturally exist in the patient’s body. With regard to transplantation, stem cells can be partially or fully cultured in a photoreceptor (cell) in the laboratory before they are transplanted into the eye. Once transplanted into the retina, the new retinal cells are able to mature and merge with the existing tissue. Thus, retinal diseases can be treated.