Eye microsurgery centre / Eye diseases / Near sight, long sight, astigmatism / What is Nearsightedness?

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Near sight, long sight, astigmatism

What is Nearsightedness?

Nearsightedness (myopia) – it is a vision disturbance, when a person sees well things in a close distance, but sees badly things in a far distance. Nearsightedness is quite widespread among children and adults. According to the World Health Organization 800 million people of our planet suffer from the nearsightedness.

Our eye is often compared to a photo camera. The role of the objective in it is played by cornea and lens: they let through the light beams, falling to the eye. The role of light sensitive film is played by retina: an image is formed due to its light sensitive cells in it. It is transformed into neural impulses and transferred along the optic nerve to the brain. The image will be focused if cornea and lens bend the beams so that the focus (the beam crossing point) is located on retina. This is why healthy people can see well in distance.

In nearsightedness light beams are collected in focus before the retina and image is not focused, it is unclear. It can happen due to two reasons:

· Cornea and lens bend the beams too intensively;

· The eye is too lengthened during growth and retina is too far from normal

· The location of focus. Normal length of a healthy human eye – 23- 24 mm, but in nearsightedness it reaches 30 mm and more. Eye lengthening by each millimetre results in increase of nearsightedness by 3 dioptres.

Specialists divide nearsightedness in three stages:

· mild – until 3 dioptres;

· medium – from 3 to 6 dioptres;

· severe – more than 6 dioptres.

Why nearsightedness develops?

There are many reasons causing development of nearsightedness. Physicians consider that the main of them are the following:

· excessive vision work in a close distance from a thing (without rest for eyes and at insufficient light);

· congenital tendency, expressed in eye-bal structure peculiarities and its metabolism;

· weakened sclera not creating sufficient resistance towards excessive growth of the eye;

· not sufficient development of the eye acommodation muscle, responsible for “setting” of the lens in different distances; too much tension of the weakened muscle also can result in nearsightedness.

Symptoms of nearsightedness

Nearsightedness develops as a rule already in childhood and is quite remarkable at school. Children start to see worse things in far distance, hardly distinguish letters and figures, written on the board, try to sit closer to the TV set, in the first rows in the cinema. Nearsighted people often squeeze eyes trying to see better things in a distance.

Also vision in dawn worsens: nearsighted people find difficult to orientate themselves on the street and to drive a car in evenings.

Nearsighted people are obliged to wear contact lenses or glasses with minus value to improve their vision. Sometimes they have to change the glasses and lenses often due to worsening of vision. However, it should be noted that wearing glasses cannot stop the nearsightedness development, they only correct the light refraction. If vision decreases and it is necessary to change glasses to stronger, it means that nearsightedness is developing. It happens due to the eyeball extension increase.

Progressing nearsightedness – it is not an innocent vision defect, which is possible to diminish by glasses or contact lenses but a disease with serious consequences.

Children, mostly of age from 7 to 15 years, often suffer from progressing nearsightedness. Extension of the eyeball results in vessel, which are located inside the eye, extension, retinal nutrition disturbances, decreased vision acuity. Retina, similar to a strained gentle veil, in some places disintegrates, holes appear in it and retinal detachment can happen. It is the most severe complication of nearsightedness when vision significantly decreases, even to complete blindness.

Dear patients, please remember! Timely consultation of ophthalmologist helps to prevent serious complications of nearsightedness and maintain vision!

Diagnostics

Only a specialist can evaluate the degree of Your nearsightedness and choose the most appropriate treatment for each case.

Ophthalmologists of the EYE MICROSURGERY CENTRE (ACU MIKROKIRURGIJAS CENTRS) will perform the necessary investigation by an equipment of high accuracy. Diagnostics of nearsightedness needs the following investigations:

· evaluation of vision acuity without glasses, choice of the necessary glasses for you;

· estimation of refraction (bending) ability of Your eyes and nearsightedness degree;

· measurement of eye length by ultrasound disgnostics. It is painless and very precise investigation, a physician can use the results to evaluate development of nearsightedness;

· measurement of corneal thickness in different points of it by ultrasound. This investigation is necessary if a refractive surgery is planned for You;

· examination of fundus oculi (ophthalmoscopy) that enables the physician to evaluate condition of retina, vessels, optic nerve of each eye.

This is a general scheme of nearsightedness patient investigation but treatment of each person needs an individual approach. Therefore the physician can administer additional examination, if necessary.

Treatment

Physicians divide the treatment of nearsightedness into following main sections:

· stopping of pathological eye growth;

· prevention of possible complications of nearsightedness;

· correction of nearsighted eye refraction, release from wearing glasses and contact lenses, if possible;

· training of the eye muscle system.

Different nearsightedness treatment methods are developed and successfully used in the leading clinics of the world: scleroplasty, collagenoplasty, laser coagulation, keratotomy, laser keratomilesis, excimer laser keratotomy, implantation into the eye of intraocular lens and many others.

Scleroplastic surgery

Scleroplastic operations are performed to stop the eye growth. Layers of biological materials are introduced behind the eyeball during the operation. They, similarly to a bandage, embrace the eye and prevent from extension. These materials grow into the vessels by time and the eye starts to receive more blood and nutrients than before scleroplasty.

A simplified operation, called “collagenoplasty”, is used in some occasions today. Its advantage is the fact that the biological materials (collagen) are introduced behind the eyeball by a canula (a polymer tube). Collagen stimulates special cells located in the sclera of an eye producing new scleral tissue that prevents scleral extension and eye growth.

Scleroplastic operations can be performed in conditions of an outpatient hospital, its length is 5 to 15 minutes. Such surgical operations sometimes are performed simultaneously on both eyes or are combined with other operations on the eyeball.

Laser treatment is performed in some cases in order to prevent complications of nearsightedness in addition to scleroplasty. A laser beam “cauterises” the retina to the vessel membrane in the weakest places and around its fissures, preventing the most severe complication of nearsightedness – retinal detachment.

When pathological eye growth is stopped and complication prevention performed, the most important question for a nearsightedness person arises: how to obtain the most natural image and perception of the world in its natural size and colours, undeformed by glasses, how to get rid of the thick lenses, creating so much difficulties, externally mutilating and internally depressing.

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