The optic nerve is part of the visual analyzer. When light rays reach the retina, there is a nerve impulse, which is transmitted along the nerve fibers to the brain. If the image of a tumor of the optic nerve, this process is disrupted, and the functions of reduced or lost completely.

What are tumors of the optic nerve

Tumors that arise from the tissues of the optic nerve, called the primary. These include glioma and meningioma. If the tumor develops from the tissues surrounding the optic nerve, and it grows, it is secondary.

Glioma - a benign tumor A benign tumor - is not always safe . It develops from the elements of the tissue that fills the gaps between nerve cells and blood vessels. This swelling may occur in any part of the optic nerve, it grows on the nerve fibers and sometimes enters the cranial cavity. Dimensions gliomas may be different from a pea to a large egg. The tumor has a spindle shape and a smooth surface, and are sometimes formed within the cysts are filled with fluid. Glioma occurs in children, but rarely develops in adults.

If the tumor is formed between the shells of the villi of the optic nerve, it is called a meningioma. It usually occurs in older people, women get sick more often. In most cases, the tumor develops a part of the nerve, which is in orbit. Meningioma invades surrounding tissue, but does not give metastases Metastasis - danger everywhere . The tumor is unilateral, but in rare cases, affects both the optic nerve at the same time.

Signs

Visual impairment - an early symptom of the disease. Man worried about loss of some sections of the field of view. Nerve fibers are squeezed a growing tumor, and because of decreased visual acuity. As the tumors visual function is gradually reduced, and the patient can go blind.

Exophthalmos (protrusion of the eyeball) - another important feature of tumors of the optic nerve. This symptom progresses slowly. The mobility of the eye in all directions is usually stored. Restoring the normal arrangement of the eyeball is difficult and in most cases not possible. If the tumor grows closer to the edge of the orbit or thicker growths appear cystic cavity, the eyeball is displaced laterally. When the location of the tumor within the cranial cavity exophthalmos occurs much later than in the localization of tumors in the orbit.

When the tumor is very large eye gap can not link up. The cornea dries up, and it dystrophic changes. This can lead to perforation and even loss of the eye.

Diagnostics

One of the simplest methods of diagnosing tumors is ophthalmoscopy - examination of the fundus with the help of a special device. Thus the doctor can estimate the state of the optic nerve (ocular nerve portion, which is formed from the processes of nerve cells) and blood vessels. When the tumor is in the early stages of development, changes in the fundus can not be. A little later due to violations of the outflow of tissue fluid edema Prevention and treatment of edema - it is important to understand the root cause   optic disc, joined atrophic changes. Sometimes there is a thrombosis Thrombosis - the cause of heart attack and stroke   central retinal vein, which is why the fundus become visible significantly narrowed artery, dilated and tortuous vein, there are multiple hemorrhages.

During the radiographic examination is determined by the extended orbit, while its walls are thin. For glioma particularly characteristic increase in the diameter of the channel of the optic nerve, bone wall which thus remain unchanged. In most cases, meningioma in a channel which extends in the optic nerve, not expanded. Ultrasound examination of the eye sockets also helps to detect tumors.

The computer and magnetic resonance tomography (CT and MRI) - The most accurate method of diagnosis of tumors of the optic nerve. They allow you to define the size and location of tumors.

Treatment of glioma

When the optic nerve glioma surgical treatment. If the tumor is located in the orbit, the orbitotomy performed (operation in which in orbit are dissected tissue and opened space, which is located behind the eyeball). Then removing a part of the optic nerve, which is struck by the tumor. If glioma does not apply to the eyeball, it can be saved. Otherwise, it is removed along with the tumor.

In those situations where the glioma sprouts in the cranial cavity, frontal bone trepanning operate (make a hole in it), then autopsied channel of the optic nerve and the upper wall of the orbit and removing the nerve segment with the tumor.

Treatment of meningiomas

Surgical treatment for meningioma performed when the tumor grows along the optic nerve and the patient at the same time completely lost his sight. Before the operation, using a computer or magnetic resonance tomography defined the boundaries of the nerve segment to be removed.

Hemorrhage in the fundus, which are identified in the ophthalmoscopy - a sign of tumor spread to the eyeball. In this situation, the optic nerve is removed together with the eye. If the tumor spreads into the cranial cavity, necessary to consult a neurosurgeon.

When you save the view or tumor invasion of the dura mater and the muscles surrounding the eye, the irradiation of the orbit. These treatments only stops the growth of tumors, but not eliminate it.

Patients after treatment for a tumor of the optic nerve once a year, the CT or MRI. This allows you to assess the condition of the sockets and canals where the nerve.

Tumors of the optic nerve should be identified in the early stages. This will allow time to provide treatment and avoid the serious consequences of the disease. Therefore, any resulting impairment - an occasion to refer to the doctor.

Alexander Chernov

Causes of astigmatism may be different. Astigmatism - is quite frequent eye disease, which is based on changes in the correct shape of the cornea. These changes lead to a breach of the angle of refraction, the disappearance of the focus, and thus to impaired vision as a fuzzy vision of objects.

What happens eye with astigmatism

With astigmatism, the rays emanating from any point of space, do not give a focal point on the retina images - Focus is more, sometimes a lot, which leads to blurring and distortion of the image. Therefore, a person suffering from astigmatism, the point may be taken as a line or an oval.

Astigmatism can occur not only in the curvature of the cornea, but also in irregular shape of the lens. Sometimes corneal and lenticular astigmatism combined. However, more important is the astigmatism of the cornea, as it has a greater refractivity than lens.

The causes of astigmatism are currently not well established, but is actively research is carried out to identify them.

The first reason - heredity

Its development is associated with corneal irregularity structure: instead of the correct spherical form in the form of a piece of the ball, it has the shape of a segment of an ellipsoid of rotation.

The light rays are refracted in such a cornea in different ways: more refracted rays coming in the meridian corresponding to the short axis of the ellipse, less - in the meridian corresponding to the long axis of the ellipse. Rays of light coming into the intermediate meridians, and accordingly refracted to different degrees. Therefore, the position of the point of the astigmatic eye is not precise, and depending on the position of the retina in relation to the light beam produces a different shape (oval, circle, line). This view is called the formation of the correct astigmatism - this pathology is more common in the hereditary nature of the disease.

Hereditary astigmatism Astigmatism - lenses, glasses or surgery?   often family. Inborn errors of the structure of the cornea typically do not change throughout life. A small degree of correct astigmatism are frequent and usually on sight does not impact - the so-called physiological astigmatism. But astigmatism largely always significantly reduces vision. Disease occurs mainly in families that already have astigmatism patients. If the mother or father have astigmatism, it is likely to be and the baby. If the family has people with astigmatism, the child should be examined as soon as possible.

In hereditary correct astigmatism, visual acuity can be significantly improved, or even brought to normal with the help of corrective glasses cylinder.

The second reason - injuries and diseases of the eye

After various injuries and burns on the cornea of ​​the eye may remain scars and areas of haze, which lead to a breach of the refraction of light and the emergence of multiple foci on the retina. Often the cause of astigmatism is an eye operation. For example, the common cataract operation Cataract surgery - surgery   sometimes complicated by the development of astigmatism, as during surgery incision around the cornea to remove the lens. This can lead to significant changes in the structure of the anterior chamber of the eye and cause the development of astigmatism. Sometimes, removal of the lens is replaced by a special toric lenses, which greatly reduces the risk of astigmatism.

Various eye infections can also leave their mark on the cornea in the form of scars and opacities, which means it can be cause of pi of astigmatism. The cornea can change its shape due to keratoconus - a disease in which a result of the thinning of the corneal dystrophy and corneal tissue receives a conical shape.

With a slight physiological astigmatism, these diseases will contribute to a significant change in the cornea. Hyperglycemia (increased blood sugar) can also contribute to the occurrence of violations of the lens. Sometimes the cause of astigmatism are the various strains of dental system (including congenital anomalies), which lead to the deformation of the wall sockets. The treatment of these diseases astigmatism can pass on their own.

These kinds of acquired visual impairment are considered irregular astigmatism. They are caused by changes in turbidity or scar the cornea. This not only its various meridians have different refractive power, but also every meridian in isolation on its various segments have different refractive power. This pathology is almost impossible to correct.

From the causes of astigmatism depends treatment of this disease.

Galina Romanenko