What is a refractive error?

The eye is an optical system, which, under normal conditions, allow images to be formed on the retina (a membrane sensorineural light sensitive lining of the eye on the inside). Each eye has a certain optical power, called refractive power. Refractive errors are anomalies of the refractive power, which make the image clearly not be projected on the retina.



Light rays enter the eye through the lens and converge on the retina.
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Refractive errors are generally constitutional (congenital), though in some cases may be secondary (or acquired). When refractive errors are constitutional, they are called ametropia.

Ametropia are myopia , the farsightedness and astigmatism . Are the most frequent cause of consultation in ophthalmology.

Why should a refractive error?

A refractive error may be due to various anomalies that affect:



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The axial length of the eyeball, or distance between the cornea and retina (axial ametropia). Are the most common.

The index of refraction of the lens (a lens inside the eye), such as refractive errors in acquired (secondary to other systemic disease or eye).

What types of ametropia are there?

Constitutional ametropia are myopia, hyperopia and astigmatism.

What are the symptoms of a refractive error?

Symptoms depend on the type and degree of ametropia. They range from simple eye discomfort, a decrease in distance vision and / or near vision.

Can myopia be a sign of other eye disease?

In some very important ametropia can be observed more often for eye diseases like glaucoma , cataracts or retinal disease .

In adults, in certain systemic diseases ( diabetes ) or eye (cataract, retinal edema may occur ...), visual changes related to an acquired refractive error.

How ophthalmologist diagnosed a refractive error?

The ophthalmologist checked visual acuity for distance vision and near vision, and controls the visual power of the eye using a device called a refractometer, which lets you know the type and degree of ametropia that have allowed each and prescribe optical correction each case.

The ophthalmologist also look for abnormalities in the retina or the lens to check that there is no other reason for the loss of visual acuity.

In children is very important to graduation as early as possible, and that an adequate correction of defects that can occur before the age of 9 allows proper development of the eye. The defects are not corrected before then make the eye is not fully developed, being able to cause amblyopia, which is what is commonly known as lazy eye. The case of children is special, since in most cases it is necessary to graduate with a dilated pupil, as this avoids forcing the eye and distort the final ranking.

What should I pay special attention?

If you notice your vision deteriorates slowly, check that corrective lenses are well adapted to vision.

If vision is deteriorating rapidly or abruptly, consult an ophthalmologist.

How do I correct a refractive error?

There is no eye drops or other drug therapy to cure ametropia. According to their own desires of each, and depending on the test that is done, the ophthalmologist can advise:

Glasses

Contact Lenses

A refractive surgery .

Should a mandatory corrected refractive error?

Optical correction of refractive error is primarily a matter of convenience, except in the activities in which security is at stake, such as driving, where it is compulsory to wear glasses.