- 1 What is myopia?
- 2 Causes and Risk Factors
- 3 How does myopia classify?
- 4 For the cause
- 5 For the clinical aspect
- 6 By degree
- 7 By age of onset
- 8 Myopia symptoms
- 9 Is myopia curable?
- 10 Diagnosis
- 11 Treatment for myopia
- 12 Complications
- 13 Prevention
What is myopia?
Myopia is an eye condition in which distance vision becomes poor when compared to normal vision and is considered the most common refractive error worldwide, with greater prevalence in recent years. Because myopia has an error in the refraction of light, it is characterized by the fact that the light focuses on the front of the retina and not on it, as is correct.
The retina is the deepest surface of the eye and has the function of collecting light. Once collected, it is transformed into electrical impulses that go to the brain, which, in turn, reads it as images. The eyeball of a nearsighted person cannot read this correctly because it is a little more elongated than normal and, sometimes, because the cornea is more rounded. With these defects, the image becomes blurred in the eyes of the individual.
Worldwide, refractive errors are estimated to be about 800 million cases out of 2.3 billion people. With regard to myopia, the incidence of the problem varies according to age, country, sex, environment, among other factors.
The prevalence of the disorder around the world is as follows:
- Asia: 70 to 90%.
- Europe and the United States: 30 to 40%.
- Africa: 10 to 20%.
- Oceania: 17%.
- South America: 6.4%.
When does myopia start?
Myopia usually begins in childhood, between 6 and 12 years of age. During adolescence, as the eyeball continues to grow, and due to various daily activities performed, the problem can quickly worsen. In this initial phase, the person needs to change the glasses and / or contact lens every 12 months or, even, in less time.
In most cases, the disease stabilizes around the age of 20 and is usually at a level that varies from mild to moderate.
Can myopia decrease?
There are rare cases in which this happens, but the degree of myopia can decrease. However, this decrease will never be very large.
Index in this article you will find the following information:
- What is myopia?
- Causes and Risk Factors
- How does myopia classify?
- Myopia symptoms
- Is myopia curable?
- Treatment for myopia
As already explained, myopia is a refractive error and it is believed that the cause for this to happen is due to a set of environmental factors related to the structure of the very long eyeball or very rounded retina.
It is known that myopia has a higher occurrence in the same family, that is, people who are children of myopic parents, most likely will develop the disease as well. In addition, recent research reveals that long periods of reading, when focusing on an object at a short distance, and also the lack of light can help in the development of myopia.
Myopia can be classified in four different ways, see below:
For the cause
Borish and Duke-Elder classified myopia as follows:
Attributed to an increase in the axial length of the eye.
Attributed to the condition of the elements of the eye. For this type of myopia, Borish also created two subclassifications:
- Curvature myopia: is caused by excessive or increased curvature of the refractive surfaces of the eye, especially the cornea.
- Index myopia: it is caused by the variation of the refractive index of one or more ocular media.
Caused by the high level of glucose in the blood and that can cause edema in the crystalline lens. This edema causes a condition in the eye called temporary myopia.
For the clinical aspect
There are several classificatory forms for myopia according to their clinical aspect:
The most common of all types, simple myopia is due to the fact that the eye is too long for its optical power.
Also known as malignant or progressive myopia, this type of myopia is characterized by marked changes in the fundus, associated with a high refractive error.
Type of myopia in which the person has more difficulty seeing in areas with low light, even if their vision during the day is normal.
Due to spasms of the ciliary muscle, the vision is blurred, causing pseudomyopia.
Also called acquired myopia, it is developed due to exposure to various pharmaceutical drugs, increased glucose levels and other conditions. Induced myopia can be further divided into two types:
- Index myopia: happens due to the variation in the refractive index.
- Deprivation myopia: when vision is limited by illumination and range or when the eye is modified with artificial lenses.
Transient myopia happens when you are focusing on something for a long time and suddenly shifts the focus to another point.
This type of myopia happens when there is excessive accommodation when looking at an instrument, such as a microscope.
Myopia, as it increases, is measured in diopters (degrees). Therefore, it can be classified from that as well.
It is when myopia has -3 diopter or less (that is, closer to 0).
It is myopia that is between -3 and -6 diopter. Those who have this type of myopia tend to have pigmentary dispersion syndrome or pigmentary glaucoma .
Myopia is considered high when it has -6 or more diopter. People with high myopia are more likely to detach the retina and develop primary open-angle glaucoma.
By age of onset
Finally, myopia can also be classified according to the age at which it started to develop.
Also known as childhood myopia, it is myopia that begins at birth and persists until childhood.
Myopia of early youth
Early childhood myopia is considered when the condition arises in early childhood or adolescence and can vary up to 21 years.
It can also be subdivided into school myopia, that is, a myopia that arises during childhood, especially when the child is of school age.
This myopia occurs between 20 and 40 years of age and, when it appears after that age, it is called late adult onset myopia.
In addition to blurred vision when trying to see a distant object, which is the main symptom of those who have myopia, other symptoms can accompany the disease as well:
- The need to squint too hard to try to see an object clearly.
- Headache caused by eye fatigue.
- Difficulty seeing when driving, especially at night.
Symptoms in children
As myopia usually starts in childhood, many children experience difficulty seeing when they are in school. Among the symptoms they have are:
- Squeeze the eye persistently.
- Need to sit closer to the television, cinema screen or the classroom blackboard.
- Ignorance of distant objects.
- Excessive blinks.
- Rub your eyes very often.
Myopia has no cure, however, if treated correctly, the refractive error can be corrected. Currently, there are different types of corrections for this error, such as the use of glasses and contact lenses, in addition to laser surgery.
If you, or your child, have found that the vision is strange and a little blurry, don’t wait to go to the doctor and be diagnosed with the problem. Among the specialists, the ideal is to consult with an ophthalmologist, as it is the doctor responsible for eye health.
In the consultation, your distance, near and intermediate vision will be tested with or without glasses or contact lenses, if you use it so that the specialist can know how good they are. In addition, other tests may be done, such as:
- Retinoscopy: the doctor emits a bright light towards your eye to see how the retina reacts to it.
- Observation of a graph through a series of lenses: through this test, you will be placed in front of a projector of letters and numbers and, from the lenses that the doctor will put in your eye, you will be able to tell which one sees the projected content best. .
How often do eye exams need to be done?
A person cannot always identify that he is visually impaired. Therefore, doctors recommend performing regular exams as follows:
If you are at high risk for developing glaucoma, tests should be performed:
- Every 2 to 4 years up to 40 years.
- Every 1 to 3 years between the ages of 40 and 54.
- Every 1 to 2 years from 55 years.
If you do not wear glasses or contact lenses, and you have no symptoms or risk of developing eye problems, tests can be performed as often as described below:
- An initial exam at age 40.
- Every 2 to 4 years between 40 and 54 years old.
- Every 1 to 3 years between 55 and 64 years.
- Every 1 to 2 years from 65 years.
Children and adolescents
For the youngest, who are usually the most affected by myopia, the frequency of eye exams is:
- During the newborn period.
- In the follow-up consultations of the child until school age.
- During school years, every 1 or 2 years.
Myopia can be corrected through corrective lenses or refractive surgery. The treatment method will be based on the degree you have or, still, whether or not you want to wear glasses or contact lenses.
Corrective lenses treat myopia so that the curvature of your cornea or the length of your eye is increased. There are two types of lenses that you can use:
- Eyeglasses: the simplest way to correct the problem, eyeglasses can be found in different models and include different lenses, such as bifocal, trifocal and reading lenses.
- Contact lenses : lenses used directly on the eyes, found in different models and materials; it is advisable to ask the doctor which will be the best one to use for your case.
- Orthokeratology: this procedure consists of implanting lenses with a design called “reverse curve”, which presses the cornea in order to change its shape. Consequently, the angle of image formation within the eyeball is also modified, correcting myopia.
Refractive surgery for myopia
For those who do not like to wear glasses or for those who have a very high degree of myopia, there is the possibility of performing surgery to correct the problem.
- LASIK ( laser-assisted in-situ keratomileusis ): through this type of laser, the surgeon makes a small cut in your cornea and removes the layers from its center. After use, the corneal retina is repositioned.
- LASEK ( laser-assisted subepithelial keratectomy ): with LASEK surgery, instead of the surgeon making a cut on the cornea, it does on the protective layer of the cornea. Once this is done, the outer layers are remodeled. Bandage contact lenses will be required to aid recovery from the procedure.
- PRK ( photorefractive keratectomy ): very similar to LASEK, unlike PRK surgery is that the epithelium will be removed. Bandage contact lenses will also be required.
- IOL (intraocular lens implant): lenses surgically implanted in the eye, it is a good option for those who have myopia considered moderate or severe.
Like any surgical procedure, these eye surgeries also present health risks, in addition to not guaranteeing that you will not actually need the glasses and / or lenses again.
Restrictions for surgery
As much as surgery is a great treatment option, not everyone can do it. This is due to the fact that some factors may hinder the recovery of the same or not facilitate at the time of the procedure.
Below, you can see what these impediments are:
- Age: if you are under 21, the surgery cannot be done because your body is still developing and, therefore, it is very dangerous to change the structure of the eyes.
- Diabetes: the disease causes abnormalities in the eyes, which can get worse after laser surgery.
- Pregnancy or lactation: in these phases, your body is full of hormones that cause small changes in vision, making the surgery much more delicate.
- Conditions that affect the immune system: having diseases such as AIDS or rheumatoid arthritis affects when recovering from the postoperative period.
- Other eye problems , such as glaucoma or cataracts.
Among the complications, there are those that are caused by the disorder itself and also those that are due to surgery.
Complications of myopia itself
- Eye fatigue.
- Retinal detachment.
- Macular degeneration.
- Reduced quality of life.
- Impaired security of self and others.
Complications of refractive surgery
- Failure to correct the initial problem.
- Side visual effects, like a halo that appears around lights.
- Dry eye.
- Infections, such as bacterial keratitis.
- Corneal healing.
- In rare cases, loss of vision.
There is no sure and specific way to prevent myopia. However, some precautions can cause the progress of the disease to be delayed, such as:
- Take the eye exams regularly.
- Control chronic illnesses, if you have them, such as diabetes and high blood pressure.
- Protect your eyes with the use of sunglasses.
- Avoid eye damage.
- Eat healthy foods, rich in fatty acids and omega-3.
- Do not smoke.
- Use corrective lenses correctly.
- Recognize the symptoms of myopia.
If you have small, school-age children, be aware of how he behaves in situations where he needs to see something from a distance, as it is at this age that myopia usually begins.
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