Hyperopia

Hyperopia or farsightedness

If you are farsighted your eyes are too short; the object that you look at is not displayed on the retina (fundus) but behind it (Fig. 1). The technical term for farsightedness “hyperopia” derives from the Greek words hyper (“excessive”) and ops (“eye”).

Hyperopic eye up to c. 40 years, view in the vicinity without accommodation

Fig. 1: Hyperopic eye up to c. 40 years
View in the vicinity without accommodation

Generally, you may see badly up close but much better (Fig, 1) in to the far distance (far-sightedness). When looking into the distance, the image would actually be displayed behind the eye and appear blurred unless the lens would bulge for accommodation. As a plus lens – here the lens in the eye – causes a shift of the image to the front, this accommodates the farsighted person to see clearly in the distance. And for “focussing” nearby objects, the hyperopic can accommodate; here as well, the eye-lens must bulge even more than when looking into the distance. The closer the object under view, the more the lens in the eye has to bulge (accommodate) to keep the vision clear.

Hyperopic eye up to c. 40 years, view into the distance with accommodation

Fig. 2: Hyperopic eye up to c. 40 years.
View into the distance with accommodation

Hyperopic eye up to c. 40 years, view into the distance without accommodation

Fig. 3: Hyperopic eye up to c. 40 years.
View into the distance without accommodation

Hyperopic vision is not to be understood as if all close-up objects are out of focus and only see in focus with glasses; the near vision is strenuous and only possible with a strong effort. The lens has to bulge strongly (similar to an auto-focus function in a camera) to produce a clear image on the retina (Fig. 4) because the curvature of the eye-lens (positive lens) causes the displacement of the image to the front of the retina.

Hyperopic eye up to c. 40 years, view in the near vicinity with accommodation

Fig. 4: Hyperopic eye up to c. 40 years.
View in the near vicinity with accommodation

If the hyperopia is not strong and you are still young, the blur in close up can thus be compensated by movement of the flexible lens in the eye. The object that you’re looking at is displayed on the retina (similar to an auto-focus function in a camera). Consequently, children and young people with hyperopia can always see in focus, but they can suffer from strain symptoms such as headaches, reading problems or slight double vision (slight squint) can occur.

The hyperopia, then, is not the opposite of myopia. In myopia the eye is too long and the image is displayed in front of the retina and may have to be moved back (with glasses). But this is possible only with minus lens glasses. Near vision is always in focus because the image with over-long eyes arrives on the retina.

If you are more hyperopic it may be that you notice problems both in the distance and near vision; you are no longer able to see clearly without glasses. The symptoms are headaches, eye pressure and so on. Then the “auto-focus function” of the crystalline lens of the eye is no longer adequate to the shortened length of the eye to compensate for and clearly reflect the image on the retina. The older you are, the more rigid your eye lens; the less well you can compensate for farsightedness. A pair of glasses is necessary. It usually happens that a hyperopia is often not discovered until later in age. A presbyopia is most often discovered with people about 40 years old.

Hyperopia is corrected with plus glasses (converging lenses; convex shape) which can cause an image to shift forwards on to the retina (Fig. 5) (e.g. sph = + 4.75 diopters).

When looking close up with glasses, the image would actually end up even further behind the retina. This is compensated by the lens in the eye. With a curvature of the eye-lens (accommodation), which is a plus lens, the image is completely moved forwards on to the retina (Fig. 6).

Hyperopic eye up to c. 40 years, view into the distance without accommodation with glasses

Fig. 5: Hyperopic eye up to c. 40 years.
View into the distance without accommodation with glasses

Hyperopic eye up to c. 40 years, view in the near vicinity of accommodation with glasses

Fig. 6: Hyperopic eye up to c. 40 years
View in the near vicinity of accommodation with glasses

 

 

 

 

 

Hyperopia at a young age may often disappear during the growth phase. Since the hyperopic eye is a little too short, it possibly can be extended and adapt to the growth.

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