While reading you inadvertently push the book away from the eyes, since can't see near, but at the same time normally consider far objects? Most likely, you have hyperopia.
Hyperopia as a phenomenon
Under hyperopia, ophthalmologists mean feature eye refraction: when her distant objects in accommodative alone are focused behind the retina. At a young age, not too strong hyperopia offset voltage of accommodation. This anomaly of view, which is a type of ametropia, suffers every fourth inhabitant of our planet. It is noteworthy that the distance one sees well only if hyperopia is associated with age-related changes, but not with congenital problem.
A long process of consideration of items near in this case often causes headaches and tension of the facial muscles.
Causes of hyperopia
One of the main causes of hyperopia is the reduced size of the eyeball, located on the Antero-posterior axis. It is noteworthy that virtually all native-born children, at first, far-sighted, but a year later, the defect disappears quickly due to the growth of the eyeball.
Senile or age-related hyperopia always caused a significant decrease in the ability of the lens to change its curvature. This statistical process starts in 30 years, but only 45-50 years leads to the decrease of visual acuity at the distance of about 25-30 cm. For sixty years, eyes on 90 percent lose their ability to accommodate.
In addition to the normal physiological hyperopia in infancy, there is a congenital form: in this case, over time the sight of the baby does not come to normal. Exacerbating this process weak refractive power of the cornea and lens.
If the child has identified the coefficient hyperopia more than three diopters, then there is a fairly high probability of development of strabismus: it causes a considerable strain eye muscles.
Age-related hyperopia is the natural condition of man, to prevent which is almost impossible, because it is associated with irreversible changes in tissues and muscles of the eye. The only output is the timely correction of hyperopia using contact methods, glasses or surgery.
The article was prepared jointly with the site ImMed.ru.