Refractive defects (defects of vision) are disorders of view in which the light rays entering the eye do not focus directly on the retina, resulting in blurred vision at different distances. The shape of the eye or the cornea or the lens stiffness associated with age can reduce power to focus the eye, making vision becomes blurred when both the objects are far and near, or in both cases.
If we are dealing with refractive defects, in the cornea and lens of the eye makes it difficult to focus light rays on the retina, and the way to improve is to correct such errors using glasses, contact lenses or eye surgery.
Causes of refractive defects
Refractive errors have different reasons depending on the problem that makes it difficult to focus the light rays on the retina. There are, among other things, eye defects such as:
- Nearsightedness – occurs when the eyeballs are too long to be able to receive corneally and lens refraction. Because of its relatively long size, light is focused before and not directly on the retina, whereby a person with this disadvantage has difficulty seeing distant objects. In children, myopia develops most often until they stop growing.
- Farsightedness occurs in people whose eyesight is too short to obtain corneally and lens refraction. In the case of this eye defect, because the eyeball is too short, the light is focused on the retina, which makes it difficult to see proximity. In children and adolescents, the lens is quite flexible, so it can try to correctly focus light on the retina (at this time it is difficult to diagnose abnormality), but with age, the lens getting stiff, and vision defects of this type are becoming more problematic.
- Astigmatism – Occurs when the cornea or lens is not correctly formed (is not perfectly circular or spherical), which may cause blurry of vision of objects at any distance (both near and distant).
- Presbyopia – occurs with age, usually around the age of 40, when the lens of the eye becomes stiffer. It reveals the difficulty of seeing nearby objects.
- Aphakia – occurs in the absence of the lens as a result of congenital malformation, ocular damage caused by injury or eye surgery in which a cataract is removed. It manifests as a distraction from vision problem at different distances.
All of the above problems of the eyes can cause vision problems to varying degrees.
A person who suffers from refractive defects, in the first place may notice that the visual image becomes blurred. Blurred vision may concern the distant objects, those nearby, and both cases at the same time. A child with myopia may have problems seeing a blackboard at school, and an older man while reading a book.
Sometimes it can appear headaches caused by frequent squinting. Children can also be seen frowning while reading, as well as excessive blinking or rubbing the eyes, which may indicate a defect of vision. They tend to be cases in which there is eye dryness, itching, redness or irritation, and the vision temporarily blurs.
Diagnosis and treatment of refractive defects
Diagnosis consists of a thorough visual examination in which visual acuity is measured. It is important, however, to have regular preventive examinations performed by an ophthalmologist, preferably every 1-2 years. In children, vision defects can easily be detected in routine screening, which is good to recognize before they begin to interfere with learning.
Refractive errors usually occur in healthy eyes, in which appear irregular structure, which is why extensive tests should also include an assessment of possible problems not related to the problems of view, as the field of vision test, the pressure inside the eye and eye movements.
The treatment involves the use of glasses, contact lenses and in some cases a surgical procedure that helps to make changes in the shape of the cornea, which can improve refractive errors.