Ophthalmology

Therapy of myopia

introduction

Nearsightedness (myopia) can be corrected by wearing glasses or contact lenses. However, this does not directly address the cause of myopia. A correction of myopia by means of laser treatment is also an option.

Glasses / contact lenses

With mild myopia, many patients choose wearing visual aids as therapy.

In myopia it is eyeball relatively too long. The incident light rays are not bundled in one point on the retina, but in front of it, so that the rays that ultimately fall on the retina are no longer centered in one point, but already scatter again. As a result, the resulting image is out of focus for the person concerned. Glasses or contact lenses are for myopic people using Diffusing glasses prepared. These have a negative refractive index and ensure that the light rays falling into the eye meet again exactly at one point on the retina. The nearsighted person then sees sharply again. For this an eye test is first of all the exact Eyesight determined by the person in order to be able to manufacture the glasses or contact lenses accordingly.

There are many different types of contact lenses. There are daily lenses that have to be changed after a day, monthly lenses that can be worn for a month, as well as annual lenses. A distinction is also made between hard and soft contact lenses. In sensitive people, however, wearing contact lenses can cause severe irritation to the conjunctiva and cornea. The result is red, dry or itchy eyes. Some people also describe a constant foreign body sensation in the eye. The longer it is worn, the greater the risk of conjunctivitis. Furthermore, the lenses should not be worn while swimming or going to the sauna, as chlorinated water and strong heat attack the lenses.

Orthokeratology

An alternative method to the ordinary contact lenses are special lenses that only at night be worn. They lead to one Flattening the cornea, which ensures improved visual acuity during the day.
To do this, the lenses need about 6-8 Hours, no visual aid is required during the day. However, this only works with a myopia of maximum -4,5 Diopters. More pronounced myopia cannot be corrected with night lenses.
A disadvantage of orthokeratology is that it can lead to a decrease in visual acuity at dusk and in the dark.

Laser treatment

The method commonly used today to laser the eyes for myopia is the so-called LASIK (Laser-assisted in situ keratomileusis). The Removal of the cornea changes the curvature of the cornea. In Germany the procedure is only possible up to a myopia of -10 Diopter approved. The more myopic the patient, the more cornea has to be removed. Accordingly, it must be of sufficient thickness and stability, otherwise the intervention cannot be carried out.

Contraindications: If the cornea is too thin or if myopia is more than -10 diopters, LASIK is not performed. Also, the patient shouldn't be under 18 years be old. The patient's visual acuity is checked several times in advance of the procedure. If the values differ significantly from each other, LASIK treatment is also not recommended. Furthermore, various eye diseases prohibit LASIK, e.g. glaucoma and cataract. Also Wound healing disorders and Autoimmune diseases speak against such an intervention.

Procedure: The procedure only takes a few minutes per eye. Before the procedure, the eye is anesthetized with special eye drops and a Eyelid locker kept open. A laser is then used to cut a thin lamella into the cornea (known as a flap), which is not completely separated, but only folded down becomes. The corneal layer underneath can then be removed with another laser. The operating surface is then rinsed and the flap is moved back to its old position. This procedure usually takes less than 30 seconds. The flap will heal within 2-3 days.

Chances of success: The chances of success with LASIK are very good. In most cases, eyesight improves dramatically right after the treatment. Far over 90% of patients achieve the desired visual acuity, and many can even do without glasses or contact lenses entirely.

Risks: As with any surgical procedure, LASIK also involves some risks. The removal of the cornea can lead to over- or under-correction of myopia, i.e. the patient does not achieve optimal visual acuity even after the procedure. It can also limit the Seeing in the dark come because the contrast sharpness can decrease. If a lot of the cornea has been removed, its stability is severely limited. This can cause the cornea to stretch through the Intraocular pressure bulges forward (keratectasia).
They also occur frequently, especially in the first few weeks after the procedure dry eyes because tear production is reduced. This may increase the risk of inflammation.

Phakic intraocular lens (PIOL)

The PIOL is one artificial eye lens, the additionally is inserted into the eye to the own eye lens. Intraocular lenses are usually used in the treatment of the cataracts for use, but they can just as well serve to correct ametropia. This method can be chosen as an alternative to laser therapy if this is not possible or if there is a high degree of ametropia.
Requirement is one Minimum nearsightedness from -5 diopters. With some lenses, myopia can be up to -20 diopters be balanced. The lenses have focal points tailored to the patient, usually one for near and one for far vision. This enables the patient to live a largely glasses-free life after the operation.

Lenses: PIOL distinguishes between different types of lenses. For one there is Anterior chamber- and Posterior chamber lenses. The anterior chamber lenses are between the cornea and iris, the posterior chamber lenses between the iris and Eye lens used. There are also hard and soft lenses. The materials used are mostly acrylic and silicone.

Contraindications: A PIOL should not be used in people under 18 years or Pregnant women can be used. In addition, the patient's visual acuity measured several times in advance should not deviate significantly from one another. In addition, if the patient's anterior chamber is not deep enough, there would be insufficient space for an anterior chamber lens to be inserted. In such a case, the procedure cannot be performed.

Procedure: The PIOL is usually outpatient and under local anesthesia inserted into the eye. A cut of 3-6mm length (depending on the lens) is required for this. A seam is not necessary.

Risks: After inserting the PIOL, there is an increased risk of the eye becoming infected. The lens can also slip out of its position as a result of manipulation of the eye (strong rubbing, strong vibrations), so that a new intervention is necessary. In addition, damage to the cornea can remain due to the incision, which leads to reduced visual acuity. The body's own lens can become cloudy. Under certain circumstances, the intraocular pressure can increase enormously. In any case, the patient must undergo regular lifelong checks by the ophthalmologist after the operation.

Conclusion

Which method the patient chooses to correct his nearsightedness is up to him. If the eyesight is only slightly impaired, glasses or contact lenses remain the means of choice. Surgical intervention is particularly useful for people who are reluctant to use such aids. This also applies in particular to people who have such severe nearsightedness that even glasses can no longer help them adequately.

Summary

A myopia corrected by lowering the refractive power of the eye and thus bringing the focus back to the Retina shifts.
You can either do this with Spectacle lenses or. contact lenses or by means of a Laser operation.
The glasses / contact lenses are concave lenses (also minus glasses or diverging lenses).
Contact lenses are elastic glasses that lie directly on the cornea. However, you have to care for the contact lenses and the cornea accordingly, as otherwise irreversible (irreversible) damage to the cornea can occur.
In the optimal case the Myopia - Therapy the weakest concave lens with which one can still see best in the distance should be prescribed.
At a Laser therapy the cornea is flattened with the help of the laser and thus the refractive power of the cornea is reduced. The operation only takes a few minutes, but it does involve some risks, especially when it comes to it stronger Myopias (From around 6 dioptres, myopia can persist despite laser treatment, or impaired vision or even complete loss of sight can occur).
Therefore, this procedure is not yet recommended for people with severe myopia. Depending on which laser method you choose, the risk is between 0.5% to 5%.