Presbyopia is a normal condition in which the eyes gradually lose the ability to focus on near objects as we get older. It is also known as age-related farsightedness. As it progresses over time, it becomes increasingly challenging to perform near tasks like reading and threading a needle.
Everyone experiences presbyopia, but the age of onset varies from person to person. Most people begin to experience the symptoms at about 40 years of age. Others experience them earlier or later. Generally, people with hyperopia (long-sightedness) tend to develop presbyopia earlier than people without refractive errors. On the other hand, those with myopia (short-sightedness) tend to get it later than those without refractive errors.
Visual impairment due to uncorrected presbyopia affects the quality of life. It causes so much discomfort and affects job performance, leading to lower work productivity and decreased income/profits.
Presbyopia is caused by the normal changes the natural lens in the eyes undergo as we get older.
When we are younger, the lens is flexible and changes its shape easily to focus on objects at different distances. While looking at an object at a distance, the lens is relaxed and flat, but when you change focus to an object nearby, the lens curves or bulges to adjust its focusing power. This helps it focus on the near objects. This process by which the lens adjusts its focusing power as you change focus from a distant object to a near one is known as accommodation.
As we get older, the lens gradually hardens making it less flexible and unable to change its shape to accommodate for near vision. Hence, vision gets blurry while performing near tasks.
- Blurry vision at near
- Difficulty performing near tasks such as reading tiny prints, threading a needle, or picking stones from grain.
- The tendency to move reading material and objects away to see clearly.
- Headaches and brow ache after reading or doing close work.
- Eyestrain and fatigue.
Presbyopia is diagnosed during an eye examination. The eye doctor will ask about complaints, symptoms, and other information related to your eye health. Then s/he will perform various tests to diagnose your condition. Two major tests help diagnose presbyopia. They are:
- Near visual acuity – a test to determine how well you see tiny prints.
- Refraction – a test that determines the lens prescription that will help your eyes focus on near objects and see clearly.
There are there major treatment options for presbyopia. They are
- Contact lenses
The first two options are widely available here in Nigeria.
Eyeglasses are the most common and cheapest means of correcting presbyopia. There are quite many options to choose from. Your choice would depend on your preference, occupational vision needs, and whether you have an existing refractive error or not.
The commonly available lenses are single vision lenses, bifocals, and progressive lenses.
- Single vision lenses are lenses that have a single prescription all over. For the correction of presbyopia, they are usually prescribed as reading glasses. This means you can only put them on when you need to do some near tasks such as reading. If you try to look at a distant object with reading glasses, you will experience blurry vision.
- Bifocal lenses are lenses that have two prescriptions on them. One prescription is located at the top of the lens (for distance vision) and the other prescription is located at the bottom (for near vision). There are different types of bifocals based on the style of the bottom or reading segment of the lens.
- D top: This is also known as flat top. The reading segment of the lens has the shape of a D turned to its side with the flat part facing up.
- Roundtop: The reading segment of the lens has the shape of a semicircle
- Invisible: Also known as no-line bifocal. It is similar to the round top but the demarcation between the distance and near segments of the lens is not visible.
- Progressive lenses are the most modern lenses available for the correction of presbyopia. The power of the lens increases gradually from top to bottom enabling the wearer to have clear vision at almost all distances. Compared to bifocals, it takes a little more time to adapt to progressive lenses and they cost more. However, they are more cosmetically appealing because of the absence of visible segments on them.
These lens types are available with additional features that protect the eyes and also improve vision clarity and comfort depending on visual needs. Hence we have different versions of the single vision lenses, bifocals, and progressives. Examples include:
- Anti-reflective lenses – These are lenses with coatings that reduce light reflections making vision clearer and more comfortable.
- Antiblue lenses – These reduce light reflection, protect the eyes from harmful blue light, and lower the risk of eyestrain.
- Photochromic lenses – These are light-adaptive lenses. They are clear indoors and darken under the sun. This helps keeps vision clear and comfortable under varying light conditions.
Contact lenses are thin lenses placed directly on the surface of the eyes. They are a good alternative for many people who have presbyopia but do not want to wear eyeglasses.
Options available include:
- Monovision lenses: These are single vision contact lenses placed in each eye such that one eye is corrected to view distant objects and the other is corrected to view near objects. With monovision lenses, you use one eye at a time depending on the distance you are focusing at.
- Bifocal contact lenses: These just like the bifocal eyeglass lenses contain two powers in one lens, one at the top for viewing far objects and one below for viewing near objects.
Refractive surgery is the third option for managing presbyopia. However, people rarely opt for it. It involves making surgical changes to the cornea and/or lens to improve near vision.
Note that after surgery, some people may still need glasses to get maximum improvement in distant or near vision.