Myopia
Myopia is very common and it is the most common form of vision error in children. It is often common for myopia to progress during young years and finally taper off in the early to middle twenties. Depending on the degree of myopia, regular examinations are usually in order. Many cases of myopia are mild and are seldom associated with other eye problem. Severe myopia however, can have associated problems often due to the eye bocomes overly elongated. When this has happened, intraocular structures as the retina can become very thin and should get monitoring on a periodic basis for hole formation and tears. Other cases such as macular degeneration, and retinal detachment, as well as glaucoma can develop with severe myopia.
Farsightedness
The human eye ability to accommodate allows for it to view and focus images of both nearby and far away objects. As mentioned earlier, the lens in the eye forms a large curvature to bring near objects in focus and a flat shape to bring distant objects into focus. Unfortunately the eye has an inability to a provide a wide variance in length and this lead to a large variety of visional defects. Most often the defect occur at the end of the spectrum, either it's the inability to assume short focal length and to focus on near objects or it is the inability to take a long focal length and therefore focus on the distant objects.
The farsighted eye
Farsightedness and hyperopia is the inability of our eyes to focus on near objects. The farsighted eye do not have any difficulty in viewing faraway objects. But the skill to view near objects demands a different shape of the lens - a shape that the farsighted eye cannot assume. Therefore, the farsighted eye is not able to make focus on near objects. The problem most often arises during later stages in our lives as the result of a weakening in the ciliary muscle or the lack of flexibility of the lens itself. These two causes lead us to the results that the lenses of the eyes can no longer take the convex shape that is needed to view near objects. The lens power to break light has lessened and the image of a near object is focused at a place behind the retina. On the surface of the retina, thats where the light-detecting nerve cells are placed, the image is not longer focused. These nerve cells therefore detects a blurred image of near objects.
The cure
The cure for farsighted eyes is based around an assistance of the lens in breaking the light. Since the lens cannot take the convex and highly curved shape anymore, that is needed to focus near objects, it needs our help. Therefore, the farsighted eye is helped by the use of converging lenses. These converging lenses will break the beam of light before it enters the eye and so it decreases the distance of the image. By helping the breaking ability of the eyes, the view of near objects is re-focused upon the surface of the retina.
As farsightedness most often is seen among adults, sometimes young people will suffer from this defect. When it occurs among young people, the causes is not often related to the fact that of the lens cannot assume a short focal length anymore. In these cases, the problem is always related to an eyeball which is shorter than usual. When the eyeball is shorter, the retina becomes closer than usually to the lens and to the cornea. What happens is this: The image of near objects is formed beyond the retinal surface. Normally the correction for these problems are the same as for older people - we use a converging lens, glasses or contacts.
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