What happens in far-sightedness, exactly?

What is it?

Far-sightedness is a condition of the eye. The most common symptom is seeing only blurry images of things that are too close. These problems can in turn lead to headaches and eye strain. Things that are further away, however, are often seen as normal.

Far-sightedness is most common in young children. It affects 8% of 6-year-olds, but the figure drops to only 1% in 15-year-olds.

What causes it?

Since far-sightedness is caused by abnormal refraction of light, it is caused by abnormalities in the eye parts that are supposed to adjust refraction depending on how far a certain object is. Possible faults can be, for example, weakness of the muscles that are supposed to adjust the convexity of the lens, and an abnormal shape of the cornea through which the light has to travel.

What happens during it?

Imagine an isosceles triangle that has one shorter side and two longer sides. Imagine the shorter side going through the lens of the eye, so that both ends match the ends of the lens. Then imagine that the peak of the triangle, that is, the angle connecting the two longer sides, touches the retina in the back of the eye.

If we take the two longer sides to be light rays, this is the ideal situation – all the light rays are collected into a tiny area in the retina which enables the production of a sharp image. Sometimes, though, the lens can cause the rays to refract in a too small or a too large angle. In these situations the peak of the triangle we imagined is situated either inside the eye in front of the retina or outside the eye behind the retina.

In far-sightedness, the lens refracts the light in a too small angle and the peak of the triangle ends up outside the eye behind the retina.

How can it be treated?

Fortunately, far-sightedness can be quite easily managed through wearing glasses or contact lenses. More “radical” interventions such as reshaping the cornea with laser eye surgery can also be considered.



Sources: https://en.wikipedia.org/wiki/Far-sightedness


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