Presbyopia

Presbyopia is the state of the eyes when the eye-lenses are no longer sufficiently flexible to see things sharply focussed in close up (auto-focus function). That means that seeing close up is blurred (Fig. 1). You have to keep everything far away to be able to see things clearly.

Presbyopic eye starting at c. 40 years, view in the near vicinity without accommodation

Fig. 1: Presbyopic eye starting at c. 40 years.
View in the near vicinity without accommodation

 

 

 

 

 

In order to be able to see clearly both in the near and far distance, the lens in the eye must change its shape for accommodation. For this, however, it has to be as flexible as possible. Even as a child, the lens slowly begins to become ever more rigid. This is partly because the dead cells of the eye-lens are not discharged to the outside, as with skin, but collect within the lens.

Presbyopia is corrected with plus glasses (converging lenses; concave shape) (e.g. sph = +1.50 diopters). These glasses have to take over the auto-focus function of the lens to the extent that the lens is no longer able to attain (Fig. 2). You need glasses (what are called reading glasses) if you have to hold things further away to be able to see them in focus.

 

Presbyopic eye starting at c. 40 years, view in the close vicinity without accommodation with glasses

Fig. 2: Presbyopic eye starting at c. 40 years.
View in the close vicinity without accommodation with glasses

The older you get, the less flexible is your eye-lens and the lens of your glasses have to be increased in strength, needed to compensate for the blurring vision. That is, the strength of your reading glasses has gradually to be increased. With a value of +0.50 diopters it makes sense to wear glasses. The value can increase to +3.00 diopters.

In myopia you wear glasses with minus lenses. Through these glasses vision at close distance with sight defects caused by age is not possible (Fig. 3), since the lens in the eye with its lack of flexibility can no longer bulge (no auto-focus function). If you are myopic, it may under certain circumstances be enough for a short period to take your glasses off for reading; that is, if the negative value of your glasses is similar to the plus-values of the needed strength of your reading glasses (Fig. 4).

Presbyopic eye from c. 40 years with myopia, view in the near vicinity without accommodation with glasses

Fig. 3: Presbyopic eye from c. 40 years with myopia.
View in the near vicinity without accommodation with glasses

Presbyopic eye from c. 40 years with myopia, view in the near vicinity without accommodation

Fig. 4: Presbyopic eye from c. 40 years with myopia.
View in the near vicinity without accommodation

If you are hyperopic (farsighted) it may be that you no longer see clearly despite plus lenses, because the lens of the eyes is not as strong or can no longer bulge. The “auto-focus function” of the eye-lens is no longer sufficient to see close up in order to compensate for the shorter length of the eye in order to place the image clearly on the retina (Fig. 5). For near vision you need a stronger/ higher plus value than for far-distant vision (Fig. 6).

Presbyopic eye from c. 40 years with farsightedness, view in the near vicinity without accommodation

Fig. 5: Presbyopic eye from c. 40 years with farsightedness.
View in the near vicinity without accommodation

 

Presbyopic eye from c. 40 years with hyperopia, view in the near vicinity without accommodation with reading glasses

Fig. 6: Presbyopic eye from c. 40 years with hyperopia.
View in the near vicinity without accommodation with reading glasses

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