If you are at least 40 and your eyes suddenly seem unable to focus on objects near you, you might have presbyopia, a refractive eye error much like myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.
Like other refractive errors, there are multiple modalities of treatment to treat presbyopia, including eyeglasses, contact lenses (e.g., daily multifocal contacts for presbyopia).
What Causes Presbyopia?
Refractive errors are caused by an irregularity or anomaly in the shape of the eye that causes it to be unable to properly bend (i.e., refract) the light that passes through it. Consequently, the light is focused incorrectly on the retina, and you experience blurred vision.
In the case of presbyopia, the lens — that small, clear, and pliable double-convex tissue behind the iris — causes the error. To be precise, aging and its effect on the lens are the culprits.
The lens helps correctly focus light on the retina when viewing nearby objects. The ciliary muscle controls the lens. When focusing on something close-up, the ciliary muscle contracts and the lens becomes thicker, more convex, or more curved.
Therefore, the pliability or flexibility of the lens and the ciliary muscle is a prerequisite of being able to focus sharply on a nearby object.
When you were younger, your lens and ciliary muscle were so flexible that at age 10, you could focus sharply on something only seven centimeters away.
However, as you grew older, the lens and the ciliary muscle gradually started losing their flexibility. By the time you were a young adult, an object must be around 15 centimeters away for sharp focus to be possible.
Finally, by the time you’re 40, an object must be at least 22 centimeters away if you want to see it clearly. It quickly goes downhill from there until, by the time you’re 60, you’d find it difficult to focus on objects unless they’re at least approximately 100 centimeters away from you.
How to Treat Presbyopia
As earlier mentioned, there are different approaches to treating presbyopia.
If your eyesight were good before being diagnosed with presbyopia, non-prescription reading glasses would do the job.
Nonprescription reading eyeglasses work through magnification, and they are available over-the-counter. If you cannot find a comfortable pair of non-prescription glasses (for instance, the magnification is insufficient or overpowering), you can go to your eye doctor for prescription reading glasses.
If your vision is good to start with (you have no other vision problems aside from presbyopia), you must put on your reading glasses only for close-up work, then remove them once you’re done.
You must get prescription eyeglasses if you have an existing eye condition, such as other refractive eye errors (e.g., myopia, hyperopia, and astigmatism). In this case, your eyeglasses will have to correct not only your presbyopia (near focus) but also other issues.
● Bifocal and Multifocal Eyeglasses
Bifocals have a clear horizontal line that divides the lens into two areas. The upper part corrects for far vision, while the lower part corrects for near vision.
● Progressive Multifocal Eyeglasses
Progressive multifocal eyeglasses, unlike bifocals, have no horizontal demarcation. However, progressive multifocal lenses may correct for far, middle, and near vision. Different areas of the lens provide a distinct focus for specialized vision correction.
Contact lenses work similarly to eyeglasses, and they are a great option if you cannot or would rather not wear eyeglasses.
● Monovision Contacts
Monovision contacts refer to a pair of lenses that do not have identical corrective powers. One of the lenses will enhance far vision, while the other will correct for close-up vision. The pair could also consist of one distance vision lens and one bifocal or multifocal lens.
● Bifocal Contacts
These are like bifocal eyeglasses in that they are horizontally segmented according to their corrective power. At the bottom belongs the prescription for near vision, while in the area from the center to the top lies the remedy for far vision.
● Multifocal Contacts
Multifocal contacts, like multifocal eyeglasses, have different areas that provide distinct focal points and can thus accommodate multiple prescriptions.
Simultaneous Vision Multifocal Contacts
Simultaneous vision multifocal contact lenses can provide different focusing strengths in a concentric or aspheric configuration.
● Concentric Configuration
In a concentric configuration, the lens is divided into alternating concentric rings. Clear distance vision is available at the center of the lens. Bounding the center is a ring for near vision, and this is similarly bounded by a ring for far vision, followed by another near vision ring.
This alternating ring configuration continues until the required number of close-up vision concentric rings have been satisfied.
● Aspheric Configuration
In an aspheric configuration, the center may have a far vision. The focus gradually transitions from the center to the periphery, from far to near vision.
The aspheric configuration also works the other way around. In this case, the center provides the full power of near vision, and the periphery provides far vision.
Prevention Rather Than Cure
Aging is inevitable. As such, presbyopia is not something you can effectively prevent.
However, you can try to stave off the degenerative effects of old age on your eyes. Consistently practicing good eye care habits, having regular eye checkups, and proactively addressing vision problems as promptly as possible can help.