What Is Optic Nerve Hypoplasia?

Optic nerve dysplasia is often a defect located at the entrance to the optic nerve, manifested as a partial or full defect of the optic nipple. If the optic nerve is completely undeveloped, it is called the ignoring nerve. In patients with optic nerve dysplasia, the retinal nerve fiber layer becomes thin or absent, and the number of ganglion cells decreases or disappears. It is generally believed that the disease is caused by the differentiation of retinal ganglion cell layer during embryonic development.

Optic nerve dysplasia

Definition of Optic Nerve Dysplasia

Causes of Optic Nerve Dysplasia

Optic nerve dysplasia may develop for some reason during the development of the embryo from the first embryonic stage, organogenesis to the end of the third month. Optic nerve dysplasia is a non-progressive congenital fundus dysplasia, which is caused by retinal ganglion differentiation disorder when the embryo develops 13 to 17 mm. If the embryonic fissure is closed before the development of the optic ganglion cells, the paraaxial mesoderm tissue cannot enter the embryonic fissure, resulting in the optic nerve not developing. It is clinically divided into two types, the first type of papillary defect combined with retinal and choroidal defects, and the second type is completely located in the optic nerve sheath and is a true papillary defect. The patients with choroidal defect also merged with hypoplasia of mesodermal tissue around the original optic bubble.

The specific cause of optic nerve hypoplasia and hypoplasia is unknown. A few are dominant inheritance, most of which may be related to the influence of maternal early pregnancy or infectious diseases. The use of phenytoin, quinine, etc. during pregnancy or infection with syphilis, rubella, and cytomegalovirus can cause it.

Optic nerve dysplasia prevention

There is no clear preventive measure for this disease at present, but considering its possible cause, pedigree analysis is performed on the families of patients with this disease, based on genetic laws, to avoid the birth of high-risk offspring; and to avoid the use of drugs such as phenytoin and quinine during pregnancy Or infection with syphilis, rubella, cytomegalovirus, etc. may have a certain significance in reducing the incidence of the disease.

History and examination of optic nerve dysplasia

Key diagnostic factors of optic nerve dysplasia

Fundus (common)

Partial or complete optic disc hypoplasia, smaller than normal optic disc, about 1/3 to 1/2 the size of normal optic disc, grayish white, may be surrounded by a yellow halo, that is, the retinal pigment epithelium passes outside the scleral sieve The edge forms a double ring sign (Figure 1). Black inner ring rises from thickened retina

The pigment epithelium is connected to the hypoplastic optic nerve, and the outer ring starts from the junction of the scleral sieve and the sclera, forming an unclear and irregular shiny white ring around the optic nipple, which is an exposed sclera or hyperplastic fibrous tissue. In most cases, the optic disc has an irregular funnel-shaped depression, the smaller one is confined to the optic nerve sheath, similar to a large physiological depression, and the larger one can be 7-10 mm deep, or accompanied by a retrobulbar cyst; the deepest part of the depression is often located below Or slightly to one side; the bottom of the depression is smooth, and the gray-white spots on the sieve plate are not visible.

The visual papilla of only a part of the defect, the central retinal blood vessels in and out can be seen at no defect, and there is no obvious abnormality, the diameter of the tube is normal; if the defect is large or nearly all of the defect, the blood vessels are tortuous or deformed, and all the retinal blood vessels exit from the defect Later, the upper branch vessels go straight upward, and the lower branch is bent down and bent downwards on the steep lower edge. This is the replacement of the retinal vasculature by the branches of the ciliary retinal blood vessels or the posterior short ciliary arteries. The sheath gap penetrates the bottom of the optic nipple defect.

2.Symptoms (common)

Vision is generally poor and is related to the degree of hypoplasia. Light vision is slightly lower or almost normal, while severe vision may be completely blind, caused by hypoplasia or amblyopia of the optic nerve. People with low vision often have strabismus and nystagmus.

Optic nerve dysplasia other diagnostic factors

Possible signs (uncommon)

Optic nerve dysplasia may be accompanied by small eyeballs, nystagmus, uveal defects, blepharoplasty, narrow punctum, strabismus, drooping of the upper eyelid, and too wide space between the eyes. There may be endocrine and central nervous system abnormalities throughout the body, such as stunting, short stature, brain hypoplasia, cranial skull, epilepsy, diabetes insipidus, etc.

Optic nerve dysplasia diagnostic criteria

It can be diagnosed according to the fundus, especially the changes in the optic nipple; if necessary, it can be combined with the results of FFA, electroretinogram, and visual field.

Optic nerve dysplasia treatment details

With growth hormone deficiency, growth hormone therapy can be applied.

In children with strabismus and amblyopia, the fundus should be checked in detail. If monocular optic nerve is underdeveloped, the covering of the healthy eye must be careful. Some people advocate the use of the healthy eye covering method to promote the function of the concave cell in the center of the macula, so that it will not be further caused by apraxia. Degenerative, but healthy eyesight must be checked frequently during this treatment to avoid deprivation of amblyopia that leads to healthy eyes.