En inglés

Hyperopia

Traslated by J.G. Provencio

	As known yet, the function of the different clear means of the eye, is to make the image we want to see to be built on the retina, the same way that the zoom in a camera has the function of making possible that the image that is to be taken to, could be drawn on the film. If formed behind or in front of it, the image will be burred.
	An hypermetropic eye is the one which, being in a rest state, forms the images coming from the infinite(5 meters —as it happens with cameras) behind the retina. Thus, the image reaching it is burred and this way will be translated to the brain.
	And what happens when looking at a near object? The rays enter the eye diverging, that is, the image will be formed further from the retina, this causing a hazier vision.
	TREATEMENT: Light rays coming from the "infinite" (from 5 meters far, I insist on this) enter parallel to one another and converge(form the image) behind the retina. It seems a sensible thing to believe that if rays entered converging, image would be formed closer to the retina, or even on the very retina. That is, vision would be less burred, or maybe absolutely clear. How do we achieve this ? By placing a convergent lens in front of the eye.

	CAUSES. And, why can images be formed in front of the retina and not in its right place?
	There are many causes. Most usual ones can be an eye-length lack or a power shortage of the clear means of the eye(due to: a change in the cornea curve-shape rate, a change on the refraction ratio of any of them—e.g. because of a metabolic disorder)
	SYMPTOMS. Could we say that an hypermetropic eye has a bad near and far vision ?
	Of course not. Not yet, because it is not that easy. We've already studied that the visual system is a dynamic matter and that there is the "accommodation" which allows the near focusing by varying the thickness (and thus the power) of the lens. As we know, when the eye resting, the hypermetropic forms the image coming from an infinite point on the retina. If the lens increased its power(which can be reached by means of accommodation), the image would be formed closer to the retina, or even on itself.
	In short, we could conclude by saying that an hypermetropic eye has a clear far vision but using an extra accommodation. If there is a great deal of accommodation(as it happens when being a child)and the amount of hypermetropia is not too big, the referred effort would not be even noticed.. If both the amount of hypermetropia and possible accommodation are big, we will have a good vision, but then astenopic bothers may appear (that is, ocular weariness, headaches, ocular irritation, etc.). And, finally, if we don't have enough of the accommodation power(because it diminishes with age, as already studied in other part of this web), we just will not be able to see properly.
	But this isn't all. We do know that nearsighted requires the starting of the accommodation process, and thus an effort has to be made. If being farsighted, much bigger the effort will be as far as near focusing is concerned and to compensate the hypermetropic effect. This is the reason for the near vision bothers in hypermetropic people appearing sooner than the far ones.
	In short a farsighted could enjoy a proper far and near vision, a clear far vision but near bothers, ; he could suffer of far bothers and near impairment, or a really bad far and near vision. All of them depend on the accommodation power ability(age) and the amount of hypermetropia this person has.
	EVOLUTION. Generally speaking, a healthy and normal eye shows a slight hypermetropia, called physiological, which doesn't annoy nor need treatment.
	As it comes to logic, during the childhood period there is hypermetropia because the eye is small and it is. This is decreasing as time goes —with the growth of the eye—until it reaches a stable state at the age of seven or eight.
	The treatment is some kind of complex thing, and it may depend on many factors as visual keenness, astenopic symptoms, kind of job, age, strabismus and even less accurate symptoms as headaches, laziness, or precocious weariness when starting work, itch, etc.
	And of course : a periodical eye check-up made by a professional practitioner is absolutely essential from the childhood.