Eye diseases: characteristics, types and symptoms.
A classification of vision diseases that can affect the human eye.
Visual problems are present in a large percentage of the world's population, with presbyopia being the most common eye disease over the age of 40.
Eye diseases such as myopia, hyperopia and astigmatism are eye problems related to defects in visual refraction, which make it difficult for the sufferer to clearly perceive objects perceived at a certain distance.
There are also other eye diseases that cause many problems in the lives of those who suffer from them, such as cataracts and glaucoma, while there are diseases that do not cause so many difficulties in everyday life, such as color blindness.
Here you will find a summary of the most important eye diseases, classified.classified.
What are the main eye diseases?
The visual refraction consists of a process in which the light, which comes from the objects of the outside, crosses the diverse parts of the eyeThis is where there are photoreceptor cells (the cones and rods), which are responsible for converting the light coming from objects into nerve impulses that reach the brain through the optic nerve, to be transformed into images.
Thus, after this process, the images of the objects are concentrated in the retina.
In cases where these light rays are projected onto the retina at one point only, so that the image created is sharp, we would be talking about a process of correct refraction, which makes an emmetropic eye that does not present any pathology with respect to refractive vision.
On the other hand, if there is a problem in this process of visual refraction, so that the eye is not able to focus the images sharply on its retina, suffering a blurred vision towards objects or people at a certain distance, we would be talking about a refraction problem.
Depending on the distance at which this difficulty to perceive objects and people with clarity is present, we would speak of a pathology or others.
Below we will see the most common visual pathologies, classified.
Diseases of vision related to visual refraction
The following is an explanation of eye diseases that occur due to some difficulty in the process of visual refraction.
1. Myopia
The visual pathology known as myopia is characterized by a blurred vision of objects that are blurred vision of the objects that are at a far distance.The person who suffers from myopia has a correct vision in short distances.
This is caused because a myopic eye is more elongated than a "normal" or emmetropic eye, so the light rays coming from the perceived objects converge in front of the retina, instead of on it, so that the images are out of focus.
No matter how hard a myopic person tries to focus sharply on a distant object, he/she will not be able to do it, the only way he/she can correctly perceive the image of distant objects is by using contact lenses or divergent glasses, although it can also be treated by means of a surgical operation performed by a specialized ophthalmologist with the help of his/her equipment, known as refractive surgery. can also be treated by a surgical operation performed by a specialized ophthalmologist with the help of his or her equipment known as refractive surgery, which will also help to correct the vision loss.which also helps to correct hyperopia and astigmatism.
Another important aspect to take into account in these visual pathologies is their degree of severity. This severity is measured in units known as diopters, therefore, the greater the degree of severity of myopia a person has, the greater the number of diopters in which it will be measured.
However, the degree of severity depending on the number of diopters, both myopia and hyperopia and astigmatism, must be diagnosed by a professional practitioner after having performed the corresponding tests on the patient, this classification being applied as a guideline, based on the sources consulted.
The degree of myopia tends to increase as the person gets older.It is essential to detect it as early as possible so that the degree of severity worsens as little as possible.
2. Hyperopia
Another eye disease related to visual refraction is farsightedness, which occurs when the rays of light projected in the eye, which come from perceived objects outside, crosses the back of the retina, whereas it should cross the retina itself..
A person with farsightedness can see objects at a far distance clearly, but objects at a near distance are blurry, objects at a near distance are blurred; on the other hand, objects at a near distance are blurred.. This visual refractive defect occurs because the length of the eyeball is shorter than that of an "ordinary" or emmetropic eye.
However, farsightedness, unlike nearsightedness, can compensate for its refractive error, can compensate for its refractive error, in part, by increasing the dioptric power of the crystalline lens, the part of the eye that is located at the base of the eye.the part of the eye between the iris and the vitreous humor, whose function is to focus on objects perceived outside.
Therefore, a person with mild or moderate hyperopia and can have a correct vision thanks to the increased capacity of the crystalline lens, so that the light rays that pass through the eye, coming from objects perceived from the outside, are focused correctly on the retina without blurred vision.
On the other hand, although the crystalline lens can compensate for the visual refraction problems of people with hyperopia, it is advisable to wear glasses so that the person does not strain his or her eyesight too much. in order that the person does not strain his sight too much because he may suffer from other problems such as eyestrain, headaches and even ocular strabismus. In addition, in case of hyperopia with a high degree of severity, the crystalline lens will not be able to compensate the visual refractive error, so the person will see blurred at all distances.
Farsightedness, if detected early, does not tend to worsen in severity over the years.if detected at an early age.
On the other hand, with the use of corrective glasses, in addition to being able to see correctly, during the child's development stage, the length of the eyeballs tends to increase and, with this, the number of diopters will decrease and may become insignificant when reaching adulthood.
3. Astigmatism
A large percentage of people who suffer from farsightedness or nearsightedness usually also have some degree of astigmatism.
When a person suffers from astigmatism perceives an out-of-focus image of objects (e.g., perceiving the edges of objects with poor definition), occurring for both near and far objects, i.e., the person has difficulty seeing subtle details of objects at both near and far distances.
Astigmatism is a visual pathology that occurs when the visual dioptric surfaces (the cornea and the lens) do not have the same curvature or convergence capacity in all their axes (e.g., the horizontal and vertical axes of the cornea are asymmetrical). (e.g., the horizontal and vertical axes of the cornea are asymmetrical).
The degree of severity of astigmatism does not usually change very noticeably during the person's growth stage, unlike with accompanying myopia or hyperopia.
In addition to the visual pathologies discussed above, there is another pathology related to visual refraction that is very common among the adult population, so it is convenient to discuss what it consists of below.
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4. Presbyopia (eyestrain)
Due to a common evolutionary aging process, the crystalline lens decreases its capacity to focus objects coming from the outside on the retina, produced by a weakening of its ciliary muscles.Most people after a certain age lose the ability to focus properly without the use of contact lenses.
It is common for presbyopia to begin at 40-45 years of age, although in some cases it may appear at an older age.
Other common eye diseases
The following is a brief explanation of other eye diseases which, although less common than those related to visual refraction, also occur in a multitude of cases.
1. Color blindness or dyschromatopsia
This visual disease causes sufferers to have great difficulty in distinguishing betweenThis visual disease causes sufferers to have great difficulty in distinguishing between certain colors, due to the fact that they have two types of visual refraction.because they have 2 types of cones when they should have 3.
There are 3 types of dyschromatopsia:
- Protanopia: due to the lack of L cones, they do not distinguish well between green and red.
- Deuteranopia: due to the lack of M cones, they also do not distinguish well between green and red.
- Tritanopia: due to lack of S cones, they do not distinguish well between yellow and blue.
Deuteranopia and protanopia are eye diseases that occur more frequently in males than in females.They are caused by genetic causes that are linked to the X chromosome.
2. Open angle glaucoma
Of the group of eye diseases that cause damage to the optic nerve, glaucoma is the most common, specifically damage to the open angle of the optic nerve.
The way in which glaucoma causes damage to the open angle is when the aqueous humor (the fluid that nourishes and oxygenates the cornea and lens) fails to drain effectively.The optic nerve is damaged, so that fluid accumulates and with it the eye pressure increases, causing damage to the optic nerve.
When the nerve fibers of the optic nerve begin to be damaged, they die and the person begins to develop blind spots in the vision. the person begins to develop blind spots in the vision.This is often known as "tunnel vision", which prevents the subject from having a peripheral vision of the environment, so that there are more dead angles in his vision than would be normal.
Therefore, the two most common symptoms of this visual disease are:
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Tunnel vision.
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Having blind spots in the side or peripheral vision.
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3. Cataracts
This eye disease occurs when A cloudiness is perceived in the crystalline lens, instead of being totally transparent, so that it does not allow the lens to focus the light well. from perceived objects to focus them correctly on the retina, resulting in blurred vision. In addition, it is an eye disease that is on the rise if it is not intervened in time.
The most common changes in vision that allow a person to detect that he or she may have cataracts are the following:
- Blurred vision.
- Double vision.
- Serious difficulty seeing at night.
- Sensitivity to light.
- Perceiving lights dimmer than normal.
- Perceiving bright colors in a dimmed way.
This disease may prevent the person from performing tasks such as reading or driving a car, among others, and may also make it difficult to recognize other people's facial expressions.
Fortunately, effective surgical methods are available today, there are effective surgical methods that allow to solve eye diseases such as this one..
Cataracts are a disease whose probability of appearing in people increases proportionally with age.
(Updated at Apr 13 / 2024)