The term "presbyopia" refers to a state in which the regulatory function of the eyes deteriorates with increasing age.
This regulatory function is performed by the crystalline body that expands when looking at an object nearby to focus on one point at close distance, but, with advancing age, the elasticity of the crystalline body degrades, rendering it incapable of expanding to the required degree.
As a result, people with normal vision and even those with farsightedness or nearsightedness wearing corrective spectacles become unable to see objects clearly at close quarters.
While the eye's regulatory capability begins to deteriorate from the late thirties, symptoms do not become apparent until the age of about 45.
Symptoms of presbyopia include "difficulty in seeing objects nearby," "the need to hold reading material further away from the eyes in order to see clearly," "inability to read for extended periods of time due to the resulting eye fatigue" and "tiredness caused by wearing spectacles."
If these symptoms arise, the use of spectacles for presbyopia is recommended.
You have probably heard it said that "nearsighted people do not suffer from presbyopia."
Unfortunately, however, presbyopia is an aging phenomenon that affects everyone in the same way. It is not, therefore, true that nearsighted people do not suffer from presbyopia, or, conversely, that farsighted people will suffer early-onset presbyopia.
That having been said, because, due to the structural mechanism of nearsightedness, in many cases, nearsighted people find it difficult to see objects in the distance with the naked eye, but easy to see objects at close quarters, such people often remove their spectacles when looking at objects nearby even after the onset of presbyopia. This leads to the common misunderstanding that "if a person can see objects at close quarters with the naked eye, then that person does not suffer from presbyopia." In fact, the truth is that cases like this are indicative of serious presbyopia since such people will have difficulty seeing objects at close quarters wearing spectacles for correction of nearsightedness.
On the other hand, in people suffering from farsightedness, the eyes also use the regulatory function when looking at objects in the distance, and even more so when looking at objects nearby. In other words, because such people originally experience difficulty in seeing objects at close quarters, the symptom of "experiencing difficulty seeing" will appear sooner in people with farsightedness when the regulatory function deteriorates.
Presbyopia is an unavoidable aging phenomenon that everyone experiences.
Nevertheless, from the health management perspective, we should make efforts to take care of our eyes through properly-regulated sleep and diet as well as moderate exercise. As far as nutrition in concerned, the intake of vitamin A, proteins and vitamin B is recommended.
Because presbyopia makes it difficult to see objects at close quarters due to deterioration of the regulatory function of the eyes caused by degradation of the elasticity of the crystalline body, the condition can be corrected by the use of lenses that compensate for the difference between the regulatory function required to see objects at close quarters and the actual regulatory function. People suffering from nearsightedness and those with farsightedness need both the spectacles they use for their original condition and reading spectacles for the aged.
To combine these two into a single pair of spectacles, multi-focal lenses known as "progressive lenses" are used. Progressive lenses are designed so that both nearsightedness and farsightedness can be corrected by a single lens.
Moreover, since the regulatory function deteriorates with increasing age, presbyopia worsens even if reading spectacles for the aged are used. In terms of lens strength, presbyopia progresses at the rate of about 4 stages in 10 years. Anyone experiencing difficulties in seeing with their current reading spectacles would be well advised to order a new pair of spectacles of appropriate power.
Everyone experiences presbyopia.
Refusing to wear reading spectacles as matter of pride will put undue strain on the eyes.
The best approach is to select lenses that match your eyes and learn to live with presbyopia.