The tendency to sight defects is most often inherited from our parents. Unfortunately, we can also work for them ourselves, not taking care of our eyes. Fortunately, today there are many options for correcting vision defects - myopia, hyperopia and astigmatism.

The shape of the eyeball resembles a small ball. Any deviations from this shape (e.g. lengthening or shortening) make it worse to see objects located close or far away, or that the image is blurry, sometimes completely blurry - regardless of whether we are looking at a ship sailing far on the horizon or we are looking at it from a distance. close up of an ant walking freely on the hand.

Eye - perfect organ

Light enteringeyereaches the cornea first. It is the outer lens of the eye. Since it is transparent, you can see the iris and the pupil through it. It consists of as many as five layers and is responsible for visual acuity. Due to the fact that it is convex, it focuses the light rays, which in turn fall at the right angle on the inner lens lying just behind it. The lens is extremely flexible. By minimally changing its shape, we can clearly see both distant objects and those right in front of the nose (this is the so-called accommodation ability).

A colored iris sticks to the lens. It is very sensitive to light. In a fraction of a second it widens - when it is very light, and narrows - when it is dark. As a result, the size of the pupil changes and the amount of light falling on the retina is regulated. The retina is the layer that lines the back of the eyeball from the inside. More than a million nerve fibers receiving information from the surface of the entire retina collect into the optic nerve. It transmits information to the brain, which interprets the signals reaching it and "tells" what we see.

Important

Over 10 million Poles use glasses, and almost a million contact lenses. Vision correction requires 41 percent. fourteen-year-olds and 49 percent nineteen-year-olds. The research of the Polish National Committee for Eye Control showed that every third high school student is nearsighted. This defect is often accompanied by astigmatism.

Eye defects

In order for us to see clearly, the light rays entering the eye through the pupil should be focused exactly on the retina. This is not always the case and then we are talking about visual impairment.

  • Hyperopia - the light rays focus behind the retina. Farsight can see objects at a distance better than those in front of him. To correct this defect, focusing lenses are used. Their power is specified in diopters with a + (plus) sign.
  • Nearsightedness- the light rays focus in front of the retina, so myopia can see objects close to it more clearly. Myopia is corrected with distracting lenses. Their power is also specified in diopters, but with a - (minus) sign.
  • Astigmatism- usually accompanies short- or hyperopia, but can also be an independent defect. You can be born with astigmatism, but it can also arise and manifest itself at any age as the shape of the eyeball changes over time. It can only affect one eye or both. The cause of astigmatism is usually an abnormal curvature of the cornea. How can you imagine it? Now, the cornea is a slice of a sphere. It should be even and smooth. Unfortunately, this is not always the case. Sometimes the shape of the cornea resembles a rugby ball and thus it refracts light more strongly in one plane (e.g. vertically) and less in another (e.g. horizontally). So there is no chance that the light rays will meet at one point on the retina. They form not a point but a line - they focus in front of, on and behind the retina. For example, the viewed image may be stretched vertically or horizontally (like in a panoramic film), and also blurry. This defect is corrected by the so-called cylindrical lenses. The power of such a lens is different in the horizontal section and different in the vertical section, e.g. -4.50 / -2.50x180 degrees and (the description applies to the same lens) -7.00 / + 2.50x90 degrees. The power of the cylinders is determined in diopters with plus or minus sign. For short-sighted or farsightedness, cylindrical lenses are fused with spherical (diffusing or focusing) lenses.
You must do it

If a child sits sideways at the TV, tilts his head when he writes or reads - most likely he has astigmatism. With his body movements he tries to "tilt" the image to his own angle of view. Do not ignore these symptoms, but go to an ophthalmologist with your child. If the defect is not corrected with glasses, it may get worse.

Ophthalmological examination to detect a visual impairment

In order to detect astigmatism, the ophthalmologist tests the visual acuity and determines the power of the lenses in diopters, and during the so-called computerized examination looks at the cornea itself and determines the power of the cylinders.

The computerized survey takes the form of a test. We look through the eyepiece and see, for example, a star or a tree, i.e. a point on which we can focus our eyesight. Whether we see a point clearly or not has no bearing onon the test result. The computer processes the light waves reflected from the eye in a complicated way and gives the result. We will find out what kind of vision defect we have, whether we have astigmatism and what degree it is.

Then the ophthalmologist puts a special frame on our nose, in which he can replace corrective lenses. Having a computer test result and a cassette with lenses of different power at his disposal, he changes them until we correctly read the optotypes indicated by the doctor (these are numbers or letters of various sizes arranged in rows). He fits the lenses separately for each eye.

If an ophthalmologist suspects astigmatism, he or she will sometimes perform a test called keratometry. It resembles a computer examination of eyesight, but in this case the computer creates a "map" of the cornea - shows where it is, for example, more convex, and where it is more concave - and then "selects" cylindrical lenses to its shape in both eye. Then the optician will fit glasses with glasses or contact lenses (so-called toric lenses).

Laser vision correction

More and more people use laser vision correction. In the case of astigmatism, ophthalmologists recommend laser correction when the defect exceeds 6 diopters or hinders normal functioning, because it is accompanied by, for example, high short- or hyperopia. One eye surgery costs 1.5-2.5 thousand. PLN.

  • Refractive photokeratectomy - PRKThis method can correct defects of +/- 7 diopters and astigmatism not greater than +/- 1.5-2 diopters. Before the procedure, we are given painkillers and sedatives, and anesthetic drops are applied to our eyes. Then the doctor mechanically removes the corneal epithelium, and then uses an excimer laser to model its outer layers with an accuracy of 1 micron. PRK takes approx. 10 minutes. At the end of the procedure, the doctor puts a dressing in the form of a contact lens, which must be worn until the corneal epithelium is restored. For several hours after the surgery, we may experience severe pain, and for the next few days we may have photophobia and problems with visual acuity. For these reasons, both eyes are not operated on at the same time, but a waiting period of at least 2 weeks for the correction of the other eye. After the treatment, we use antibacterial drops to prevent eye infections. The final shape of the cornea is established approximately six months after the operation and only then can its effects be fully assessed. After correction with this method in 95-98 percent. in cases, you can do without glasses.
  • LASIKThis method can be used to correct myopia up to -15 diopters, hyperopia up to +6 diopters and astigmatism up to +/- 6 diopters. Both eyeballs can be operated simultaneously. Before the surgerywe get painkillers and sedatives, and the eye is numbed. The doctor then places a small ring around the cornea over which a device called a microkeratome moves. It cuts the outer corneal flap to form a thin flap (the movement resembles cutting the tip of a boiled egg). The surgeon tilts it and the laser models the deeper layers of the cornea beneath it. At the end of the procedure, the corneal flap returns to its place. It all takes 15-30 minutes. For a few hours after the procedure, we can feel pain and "something" can hurt in the eye. However, these ailments disappear within 24 hours and visual acuity returns. Antibacterial eye drops must be used for some time after surgery, but the risk of infection is much lower than with PRK, because the top layers of the cornea protect the altered interior like a good dressing.
  • LASEKThis is a variation of the LASIK method. Both can correct vision defects of the same size. Both eyeballs can be operated simultaneously. After anesthesia and immobilization of the eye, the doctor places a small ring on the cornea. The corneal epithelium is separated by a special substance and then folded back by the surgeon who shapes the cornea with a laser. The epithelial flap then returns to its place. The procedure takes approximately 20 minutes. Until the eyes heal, you need to wear dressings in the form of special contact lenses and use antibacterial drops. We may feel pain for several or several hours after the procedure. Visual acuity returns after a week - until then you cannot work or drive.

Surgical vision correction cannot be used by:

patients with glaucoma, cataracts, bacterial and viral inflammation of the eyes, diabetes, dry eye syndrome, severe allergies and those who have changes or degenerations of the retina with a predisposition to its detachment, permanent traumatic damage to the cornea in the form of scars, take medications impaired healing (so-called corticosteroids),

  • people who have an unstable visual defect, i.e. it has changed in the 12 months before treatment. When the defect tends to worsen, surgery could bring about a temporary improvement,
  • people under 20 or over 65.

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Eye diseases and vision disorders