Astigmatism: The Nature, Diagnosis, Treatment & Prevention
Astigmatism is a congenital inability to focus the eyes on an object properly. Normally, the light beam must be focused on the retina. In astigmatism eye instead of a single focused point, formed a few ones, and the image looks a bit blurry.
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The reason for this type of refractive error (imperfect refractive power of the eye) is the innate power section mismatch of cornea and retina. Astigmatism is often accompanied by eye ametropia other view - farsightedness and nearsightedness. The name of the disease comes from the Greek term ‘stigma’ (point).
Besides fuzzy vision subjects, patients with astigmatism usually complain of headaches and eye fatigue. These results in systematic overvoltage eye muscles when visual work. It is believed that about one sixth of the world's population suffers from astigmatism varying degrees of severity.
Intensity of astigmatism depends on the difference between the two main meridians of the eye. The longer the focal line between the rear and front focus of the eye, the worse visual acuity. Most often, this pathology causes abnormal structure of toric cornea. This form of astigmatism, respectively, called corneal astigmatism.
Astigmatism in turn happens in forward, backward or oblique axes depending on the location of the meridians in vertical, horizontal or oblique line. There is also a classification of types of astigmatism eye, depending on the focus position relative to the retina:
- Complex myopic astigmatism occurs in the presence of the main focus of the localization front of the retina.
- If one focus is in front of the retina, and the other directly behind it, astigmatism considered to be a simple myopic view of refractive error.
- Mixed hyperopic astigmatism is formed at the front focal point in front of the retina and the back focus located behind it.
- Difficult hyperopic astigmatism is diagnosed at the location of both tricks behind the retina.
The most rare form of the disease is acquired astigmatism. It is formed as a result of the injury, a serious eye disease or poorly conducted eye surgery. In this form of refractive irregular ametropia, the main meridians are not allocated, which greatly complicates the treatment.
Diagnosis of eye astigmatism
Despite the fact that the astigmatism is usually congenital disease, it is most often diagnosed in the second year of life. At this age the doctor is able to make a prediction of further development of the system of visual organs in the child.
In the diagnosis of astigmatism fundus examination is used, visual acuity test using tables and skiascopy or shadow sample is conducted. More accurate measurements of the degree of distortion can be figured out due to refractometry. The procedure is fully automated, painless for the patient and allows using special computer equipment with maximum precision to measure the optical power of the eye with astigmatism.
There is a number of fundamentally different approaches . Optical vision correction at astigmatism involves the use of glasses or contact lenses. Points - the simplest and most cost-effective method of treatment of astigmatism eye, but it has several drawbacks: limiting the lateral view, the violation of spatial perception, discomfort when wearing, etc.
Contact lenses - a more comfortable method of correcting astigmatism. Yet their use is also associated with opred¸l¸nnymi inconvenience. This sensation of a foreign body in the eye, the chance of infection or injury to the eyes.
Surgical treatment of astigmatism is also possible. The most radical surgery for astigmatism - is astigmatic keratotomy, or AK. The procedure implies making deep cuts around the perimeter of the cornea, thus allowing adjustment of the curvature of the cornea. This type of surgery for astigmatism is used in patients with a coefficient of less than 2D. However, the method is greatly inferior to the effectiveness of laser technology.
A similar procedure to change the curvature of the cornea can be performed using a laser, removing them tissue layers of the eye. This type of surgery for astigmatism less traumatic, however, and after the patient needs a long period of recovery.
The most effective among the operations of astigmatism is considered a technique of laser keratomileusis. Its essence is to create a new lens under a protective layer of the cornea. Laser surgery for astigmatism, LASIK and REIK can be carried out already in early childhood with poor tolerance of optical treatment of astigmatism.
Prevention and treatment of astigmatism in children
Defocused image with astigmatism in children can cause suppression of the visual system and a distorted perception of visual images. As a result, there is a secondary decrease in visual acuity, the development of amblyopia (lazy eye) and other complications in children.
The prevention of these diseases can be achieved through early physiotherapy, optical, and in rare cases, surgical treatment. An early initiation of therapy in most cases, significantly improve visual acuity, and eventually get rid of the spectacle dependence.
However, it is important to remember that conservative therapy can only improve the performance of the eye and to some extent compensate for the shortcomings of refraction. With a high degree of astigmatism in children can eliminate the defect of the cornea using only surgical methods.
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