What are refractive errors?
To achieve clear vision, light rays pass through the structures of the eye and are focused on the retina. The cornea along with the crystalline, are responsible for diverting or "refracting" the light rays coming from outside to get them to reach perfectly focused on the retina, specifically its later region, the taint. The retina receives the image formed by the light rays and sends it to the brain through the optic nerve, in the form of electrical stimulation.
But when we experience refractive errors, light can not concentrate in the proper area of the retina because the optical structure of the eye has an imbalance. In this way, the image sent to our brain by the optic nerve is distorted. This condition can affect our vision from a distance, up close or distort visibility in a general way.
Most Common Symptoms
The most common symptoms of refractive errors are blurred vision and discomfort or visual fatigue. Depending on the type of error and its progress, other symptoms may also occur, such as headache, auras around bright lights or double vision.
Both myopia, as farsightedness, astigmatism and presbyopia, are fully correctable with the use of glasses or contact lenses adequate or, currently, by surgery.
Types of refractive errors
The most common refractive errors are myopia, in which the patient experiences poor distance vision, hyperopia, where vision problems occur when trying to focus closely, and astigmatism, which causes a distortion in vision due to the shape Of the eye.
Added to this group is presbyopia, an eye disorder that appears when the lens wears out and is unable to focus properly, being common after the age of 40.
When the refractive error is due to a simple misalignment of one of the optical structures of the eye, it is considered benign, so it can be solved with the use of contact lenses or surgery. However, if the defect that occurs is very high, with diopters greater than 8, it could be a malignant or pathological refractive error. In these cases, in addition to correcting the optical problem, strict ophthalmological control must be maintained to avoid the presence of other alterations.
Myopia: bad vision from afar
La myopia It occurs when the eyes can see close objects clearly, but cannot clearly identify distant objects. This condition can occur due to an increased length of the eyeball, an excessive curvature in the cornea, or a change in the shape of the lens.
The hereditary factor or the family history are those that most influence the appearance of myopia. This condition is often evident in children around eight or ten years of age, increasing during adolescence along with body development and growth and stabilizing when they reach adulthood.
Other factors that can influence the development of myopia are reading or performing tasks with poor or inadequate lighting, as well as nutritional deficiencies.
Myopia can progress rapidly for a few years, but afterwards the variations are small. Between 20 and 40 years of age the changes are minimal, and may increase again around the age of 60, coinciding with the onset of a cataract.
myopia treatment
The most used option to treat myopia are glasses or contact lenses. In both cases the healing of the disease will not occur, but it will be possible to re-establish the focus of the light on the retina allowing the patient a normal vision while using either of the two alternatives.
In addition to the use of glasses or contact lenses, refractive surgery to correct myopia has become one of the most popular solutions. The most known and revolutionary technique at present is the so-called laser myopia operation, in which an excimer laser is shaped and corrects the corneal curvature, modifying the refractive power of the eye and, with it, focusing the light on the retina in a timely manner. This technique has shown good results, with great effectiveness, although tampoco is free of risks, especially those related to the maneuver of corneal carving with the microkeratome.
Other alternatives is the implantation of ICL intraocular lenses, especially for high myopia or in cases of very fine cornea, where the laser cannot be applied.
Hyperopia: poor near vision
It occurs when we experience relatively good distance vision but have difficulty distinguishing objects up close. In this condition, the eye is usually shorter than normal, making it difficult for the lens to focus nearby objects sharply on the retina. To a lesser extent, a flattening or thinning of the cornea can also cause farsightedness.
Normally, all children of childhood age are hyperopic to a moderate degree, but the condition diminishes during adolescence, when the eye develops in the same way as the rest of the body. Young people affected by this condition can usually see well both at a distance and up close, since the focusing ability of the lens during youth is powerful enough to compensate for the optical imbalance.
Children usually do not have visual symptoms such as headaches or other types of visual fatigueHowever, loss of interest in reading can be a first warning of the existence of a certain degree of hyperopia that requires a visit to the ophthalmologist and the prescription of glasses for correction.
It must be remembered that this condition, like myopia, also has a hereditary basis, so if the parents suffer from hyperopia, it is necessary that from the age of 3 the child see an ophthalmologist annually to rule out its presence or treat it in case if necessary.
Treatment of hyperopia
Hyperopia is usually corrected by using glasses or contact lenses, if you are looking for definitive results then you should resort to the laser farsightedness operation.
The correction of small hyperopia in children, especially when they have no other visual symptoms, is not necessary. In these cases it is recommended to carry out a periodic check-up by the ophthalmologist. Only in those cases of high hyperopia or associated to an ocular deviation will they need to be treated with glasses, contact lenses or surgery.
Astigmatism: distorted vision
El astigmatism It is usually caused by distortion or irregularity of the cornea. In the case of normal vision, the cornea is usually uniform and similarly curved in all directions, with a nearly spherical surface. When an individual suffers from astigmatism, the cornea is deformed and is more curved in one of its axes, the effect of this condition on the perception of figures is similar to that observed when we look at a mirror with a wavy surface, such as those found in parks of attractions, which make us see ourselves distorted as we really are.
Astigmatism is usually hereditary, being present at birth and often do not suffer large variations throughout life. The majority of the population has a certain degree of astigmatism and often does not require correction with glasses or contact lenses, which is called physiological astigmatism.
Astigmatism treatment
Normally, the blurring caused by astigmatism is corrected using glasses or contact lenses. Rigid or gas permeable contact lenses correct astigmatism better than soft contact lenses, but there are also soft lenses that solve it and that can often be of great help.
The correction of astigmatism is not difficult if the distortion comes from a regular and defined deformation in the cornea. In these cases, by means of a similar compensatory deformation in the glasses or lenses, the distortion of the cornea can be neutralized, in the same way we can definitively correct it with the astigmatism operation, using the laser to mold the cornea until the surface is regularized, transforming it into a spherical one.
On other occasions, a scar resulting from trauma or surgery can cause the deformation of the cornea to be irregular. The so-called irregular astigmatisms are more difficult to correct since it is not possible to make a glass or lens that compensates for this deformation. If the injury is very severe, it can only be improved by recomposing the cornea through a cornea transplant. Currently we have laser systems that allow remodeling a certain degree of irregularities and, although it does not solve all cases, many of them can be solved without resorting to a corneal transplant, with the drawbacks that this entails.
If the amount of astigmatism is high, lenses that correct this condition can cause distortion in side vision, so high powers of astigmatism tampFew are easily correctable with contact lenses, since the lens can tilt on the corneal surface. We currently have contact lenses known as toric lenses, which can better solve this problem, they remain stable thanks to a modification in their posterior curvature that adapts to the anterior face of the cornea, improving its stability. The anterior face of the lens is reserved to incorporate the optical modification that will correct astigmatism.
Presbyopia or tired eyesight
As people age, they experience greater difficulty focusing on nearby objects, making reading glasses necessary or doing activities that require good close-up vision. This condition is called Presbyopia or eyestrain.
Many people do not suffer from near vision problems until after the age of 40, when the lens loses some of its flexibility and cannot clearly focus on nearby objects.
Treatment of presbyopia
Presbyopia is a disorder that is normally corrected with glasses or contact lenses or, more recently, with laser surgery for presbyopia or intraocular lens implants. Once it starts it will progressively increase until the 60 or 70 years, so generally you must adjust the graduation each 3 or 4 years, especially when it appears. The glasses or multifocal lenses they can be the solution for patients who suffer from another refractive error such as myopia, hyperopia or astigmatism.
How to know when to go to the ophthalmologist
En Área Oftalmológica we care about your ocular wellness, so if you experience changes in your vision it is important to go to a specialist. Some of the signs of refractive errors that can indicate that it is time to go to the ophthalmologist are:
- Blurry vision.
- Difficulty focusing on objects near or far.
- You squint your eyes in order to focus better.
- Feeling of eyestrain very often.
- Perception of auras around very strong lights.
- you experiment stinging eyes or frequent headache.
- In the case of children, difficulty reading or decreasing the habit of reading due to lack of desire, which may indicate a visual problem.
If you experience one or more of these symptoms, do not hesitate to see a professional.
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