Myopia or Short sight
Myopia occurs when light is focused in front of the retina. It occurs because either the eyeball is too long, or because the cornea is too curved. Despite maximum flattening of the lens, the eye is not able to focus the light rays further back, and on to the retina. Myopia is when people see near objects more clearly, but distant objects are blurry. It occurs when light rays entering the eye are focused in front of the retina instead of directly on it. Myopia is usually a result of the curvature (power) of the cornea being too strong or the length of the eyeball being too long. Myopia is often inherited; it usually starts in childhood and typically stabilizes in the late teens or early adulthood.
Improper reading habits are possibly the commonest cause of short sight. Sometimes, it can be due to lack of vitamins. Myopia can also be a hereditary condition.
Myopia is best treated with eyeglasses or contact lenses which compensate for the elongated shape of the eye allowing the light to focus properly on the retina. Refractive surgery is another option which can reduce or even eliminate your dependence on glasses or contact lenses. The most common procedures are performed using an excimer laser.
Long sight, Farsightedness or Hypermetropia
Long sight, farsightedness or hypermetropia is vision disease in which an individual can see long sight object, but the object closer seems blurry.
Refractive errors can be corrected with contact lenses and eye-glasses, including long-sightedness. The lenses in glasses converge the light rays, moving the focus back onto the retina.
Young people who are slightly long-sighted generally do not have problems. If they do, they may need glasses for close work such as reading and using computers.
Older people, or young people with significant hypermetropia, often have problems because focusing requires a lot of effort. Their vision is more likely to be blurred, especially for close objects, and they usually need glasses for reading and sometimes for distance vision.
For people with significant long-sightedness, contact lenses can be the best form of correction as they provide better vision and may be preferable to wearing thick glasses. Contact lenses can be made from different materials and can be disposable or non-disposable.