Astigmatism

Definition:

Astigmatism is common and easily treated imperfections in the eye. Occurs when the front surface of the eye (cornea). Astigmatism can accompany myopia or hyperopia. As a rule, leads to irregular shaped cornea.

Astigmatism in optical system, where the air that propagate perpendicular to the two planes have different centers. If the optical system of astigmatism is used for imaging the cross, vertical and horizontal lines will focus on two different distances.



Types of astigmatism:

* The third class deviation, which occurs in subjects from the optical axis. This type of deviation occurs even when the optical system is perfectly symmetrical. This type of deviation may be known as «monochromatic deviation", because even there the light wavelength.

* Other types of astigmatism occurs when the optical system symmetrical about the optical axis. This may be due to manufacturing defects on the surface of the components or misalignment components. In this case, astigmatism is observed even the rays of a point on the shaft. This form of astigmatism is extremely important, science and vision, Eye Care, as the human eye often presented this aberration. The reason is a violation shaped cornea and lens.

Astigmatism symptoms:

It is important to examine your eyes regularly to identify early astigmatism.
* A little blurred vision.
* Uncorrected astigmatism can give you a headache, or eyes.
* Distortion or blurred vision in all distances.
* Your eyes may feel tired or dry.

Causes of astigmatism:

* Regular astigmatism, the meridian, which are two different curves lie at 90 degrees. It is very easy to correct.
* In irregular astigmatism, the two meridians may be located in more than 90 degrees. It can be difficult to correct, depending on the seriousness of the irregularity.

Treatment:

There are three methods to correct for astigmatism.

1) Astigmatism can be corrected with the use of properly placed on the glasses or contact lenses.

Prescription of three parts looks like this: -2.75 -1.25 90
* The first part indicates the main spherical correction, or the amount of power (in diopters) required the lens to improve their visual acuity to an acceptable level, usually 20/20.
* The second part shows the astigmatism in diopters. Again, the minus sign means a concave lens is required.
* Part three axes (IN category) by the piston for a bend light rays, which are spherical shape of the cornea.

2) astigmatism can be corrected procedure called refractive surgery to reshape the cornea. operations are
* Laser Eye Surgery
* Photo refractive Keratectomi (PRK)
* Using laser subepithelial keratomileusis (Lasek)

3) Last, but not less than the laser treatment. You should consult your doctor all the previous design.