Presbyopia (old man's eyes, short arms disease) disease that occurs mostly in people older than 40 years and attributable to changes in physical and chemical composition of the lens (dehydration, compaction, loss of tissue elasticity and so on. d.). All these processes lead to a breach of the accommodation process.
The eye is a complex integrated optical system, through which a person can clearly see objects at different distances.
Image forming process, which we see starts with the transmission of light through the cornea of the eye (lens with a high optical power). Then, after passing through the transparent aqueous humor in the anterior chamber, the light bursts into the opening in the iris, the diameter of which depends on the amount of light. This hole is the pupil of our eye.
Lens - the second lens in the optical system after the cornea - accurately focus an image on the retina (Perceives it upside down and converts electromagnetic radiation in the visible spectrum nerve pulses). Further nerve impulses along the optic nerve to the visual analyzer reach the brain, where the final processing occurs resulting image.
At a young age the lens is able to change its curvature and optical power. This process is called accommodation. In other words, it is the eye's ability to change its focal length, so that the eye can see and at the same time a good distance and near. With age, the accommodation is broken. This process is called presbyopia.
Causes
Presbyopia is the natural aging process of the lens. These age-related changes occur immediately, but gradually.
But there are other opinions about the etiology of this disease. This is due to the fact that not all people who have reached the so-called presbyopic age, there is a reduction of vision. And also the fact that this violation can be prevented and eliminated.
One of the theories is proved that the "tension" eye with the aim to see the printed text the focus is shifted forward. Therefore, a person can not see the picture clearly. In addition, there is pain, discomfort and fatigue. In that case, if the "stress" will be able to take off for a long time, you can restore lost vision.
Another theory states that diseases such as presbyopia, does not exist, but this state caused by a form of farsightedness - in the case where the combined reduction of both the distance and near.
In the third theory of presbyopia associated with malnutrition and deficiency of vitamins, especially the group B, and vitamin C. Treatment in this case is carried out with the help of diet and simple exercises for the eyes.
symptoms of presbyopia
- When working with small items, they are difficult to see (eg, hard thread a needle).
- Decrease the contrast when reading small text (letters acquire gray shade).
- There is a need for more bright and direct light for reading.
- To read the text, you need to take him to a great distance.
- Fatigue and eye strain when reading.
However, in people with myopia and hyperopia presbyopia it manifests itself in different ways. In patients with congenital long-sighted vision is reduced with age, both near and far. But in people with myopia (myopia) Presbyopia process may go unnoticed. So, with a little myopia order -1D; -2D, there is a cancellation of the two processes, and people will need to purchase reading glasses much later. At higher degrees of myopia, about -3D; -5D, most likely the person will not need these glasses. People with such a degree of myopia wear glasses for distance and takes off his glasses for close work.
Diagnostics
Diagnosis Presbyopia is different from other types of diagnostic refraction disorders (refractive power the optical system of the eye, expressed in units - diopters), such as nearsightedness or farsightedness. For the diagnosis of reducing near vision can take the test at home.
Here is the image of Landolt rings:
- Put on glasses or contact lenses if you use them.
- You must sit at least 35 cm away from the computer screen.
- Look at the image of both eyes open.
- Make a note of which side there is a gap in the rings (right, left, up, down)
- If you do not see all the rings correctly, repeat the experience the next day.
- If on the second day, you did not see the ring again correctly, it is advisable to consult an ophthalmologist.
presbyopia treatment
For the correction of presbyopia with visual impairment use glasses or lenses. If a person has previously been no vision problems, the need for reading glasses. If glasses or lenses previously used, you need to change them. Convenient to use bifocal glasses, the lenses are composed of two parts. The top is designed for distance vision and the bottom for the near vision.
Furthermore there trifocals and progressive lenses that create a smooth transition between the distal, intermediate and close vision.
Another option - the so-called monovision (one eye is adjusted to near vision, and the second - the distance). If there is no desire or ability to wear glasses or contact lenses, you can solve the problem of presbyopia with the help of surgery.
The methods of surgical treatment of presbyopia include of LASIK (laser in-situ keratomileusis) and PRK (photorefractive keratectomy). Both of these methods consist in the application of the laser to change the shape of the cornea. This allows one eye "tune" for near and the other - to give. It should be emphasized that the artificially created monocular vision - the patient sees well with one eye either near or far. And still need to be able to get used to this sight.
Another surgical treatment for presbyopia is to remove the patient's own lens and implantation of an artificial lens. However, an implantable lens imposes serious restrictions on the patient's lifestyle.
