It is characterized by local changes in the refractive power of different segments of one meridian. Can be inherited.Ģ - has a corneal origin. In most cases - is a congenital disorder and does not change during the life. Classification of astigmatismġ - the same refractive power throughout the meridian. Often suspect the presence of astigmatism can be in determining in visual acuity with test tables: due to the peculiarities of refraction of rays in the eye, a person suffering from astigmatism can wrong call the big signs and letters on the table and correctly distinguish smaller, which is not typical either myopia or hyperopia. less common - a chronic inflammation of the eyelid margins.The main manifestations of astigmatism (symptoms of astigmatism): If one of the meridians is emmetropic it called the simple astigmatism. Under such conditions, the eye will not have a single focal point and clear images of the objects.Īstigmatism can be also associated with a change of the shape of lens. However, it is so rare, that in practice it does not take into account.ĭegree of astigmatism is the difference between the refraction of the main meridians. Meridians called circles passing through the anterior pole (center of the cornea) and posterior (symmetrical to the front pole point in the posterior part of the eye) pole of the eye. In astigmatism curvature of the cornea is irregular and therefore one of meridians will have maximum refractive power and it perpendicular will have least refractive power . The essence of astigmatism is in unequal refractive power of the optical system of the eye in different meridians. Написала Левина Дарья, последняя правка от Īstigmatism is a refractive error (ametropia) that occurs when parallel rays of light entering the nonaccommoding eye are not focused on the retina.
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