No doubt, you will have recently observed vast numbers of people staring at cell-phone screens on trains.
Some people are sending e-mails or text messages while others are engrossed in games featuring unbelievably tiny images on their small cell-phone screens. Very few people would deny that the cell phone has become an indispensible item in our daily lives.
Have you found recently that you are having greater difficulty in seeing your cell-phone screen clearly and that can see more easily if you hold the phone further away from your eyes?
If this is the case and you are over the age of 40, you may be well advised to have your eyes checked.
If you are having difficulty in seeing objects at close range, you may be suffering the onset of presbyopia. Although the age at which symptoms manifest themselves differs from person to person, presbyopia affects everyone at some stage.
We are all reluctant to acknowledge the onset of presbyopia.
Nevertheless, to ensure good vision further down the line when we reach our fifties or sixties, it is important to get used to wearing spectacles for correction of presbyopia as soon as possible after noticing the telltale symptoms.
Although it is generally recognized that presbyopia sets in from about the age of 40, many people do not start wearing spectacles for correction of the condition until around the age of 45.
People over the age of 40 experiencing the following symptoms probably have presbyopia.
Reaching the stage where we find that our eyes tire easily or we have difficulty in seeing clearly makes us all aware of our age, in other words, the process of aging, and this can be a little depressing.
The type of lens we will be looking at here is the "progressive lens."
This type of lens has no visible boundary lines between different prescription segments and allows the wearer to see objects in the distance, in the intermediate distance and at close range through a single lens, making it the mainstream lens for correction of presbyopia today.
Although not common nowadays, lenses with visible boundary lines between different prescription segments are also available, known as "bifocal (trifocal) lenses."
These types of lens are not very appealing in terms of appearance since a person can tell at a glance that the wearer is suffering from presbyopia.
In terms of performance, while these lenses give a wide range of near vision, objects in the intermediate distance may be difficult to see because they "jump" at the boundary line.
Let's move on now to take a look at several different types of "progressive lenses."
This is a very convenient type of lens that allows the wearer to focus on objects both at close range and in the distance through a single lens and eliminates the irksome need to frequently change spectacles.
This type of lens is designed to enable viewing of objects in the distance, at close range and in the intermediate distance with corresponding changes in power for each distance.
Initially, these variations in power can, however, give the wearer uncomfortable feelings of swaying or distortion, or a sense of a narrow field of vision. (Almost all users quickly adapt and become accustomed to the variations in power.) Since these problematic sensations of swaying, distortion or narrow field of vision become more pronounced the greater the power of the lens, it is important to start using this type of lens from the 40's before the additional power (presbyopic strength) becomes too great.
Once the additional strength increases to a certain degree, it may be difficult to become accustomed to the lens and the process of adjustment may take some time.
Developed for indoor and interior use, this type of lens allows the wearer to view objects from a distance of about 3 - 4m ahead to objects at close range without removing the spectacles.
Spectacles using this type of lens are, therefore, ideal for homemakers, for example, when watching TV, cleaning, cooking or reading. Moreover, this lens is also ideal for looking at whiteboards and documents at close range for example during meetings.
When ordering an intermediate-distance bias pair of spectacles for the first time, we recommend that you actually try out a trial lens to ascertain "the range of vision this type allows and viewability" before proceeding with purchase.
Problems with viewability may gradually begin to manifest themselves if you do not first try out the lens before placing an order.
Although this type of lens features less depth than the intermediate-distance bias type, it gives a wide field of close-range vision. This lens may be thought of as an intermediary type between the ordinary single vision lens for correction of presbyopia and the intermediate-distance lens. This type is ideal for people needing a wide field of close-range vision for desk work. For example, the ordinary single vision lens gives the wearer a field of vision of no more than about 30 cm ahead, and while this enables the wearer to see the keyboard when working on a computer, it may be difficult to see the monitor. The close-distance wide lens eliminates this problem, making it ideal for users working on computers.
For those of you who have begun to think that it might be a good idea to look into spectacles for correction of presbyopia, let's take a look at points regarding when to start using such spectacles.
【 1 】 People starting to use spectacles with progressive lenses once they have reached the age of 50 may find it difficult to accustom themselves to their new spectacles and the process of adjustment may take some time.
It is, therefore, important to begin wearing spectacles with this type of lens from about the age of 45 while the additional power is still low.
【 2 】 A person past his mid-fifties will find it difficult to handle all situations with a single pair of spectacles, unnecessarily complicating his visual lifestyle.
To address this problem, it is important to distinguish between the use of different types of multi-focal spectacles by using intermediate-distance lens for indoor use at home or at work and close range spectacles when working with a computer or reading, for example.
【 3 】 Since presbyopia worsens with increasing age, it is important to be aware of the need to buy new spectacles once every 2 or 3 years. Having your eyes checked at an optometrist's twice a year, once in spring and once in autumn, is recommended.
When you have made the decision to order a pair of spectacles for correction of presbyopia, what should you keep in mind when explaining to the store assistant what you want?
In addition, what kind of store should you go to place your order?
Let's enumerate some of these points below.
【 1 】 Since you need to order a pair of spectacles that match your lifestyle, be sure to accurately describe the purpose for which you will be using your spectacles before having your eyes tested.
For example, up to roughly what distance do your need to be able to see clearly?
At what distance do you look at objects at close range and in what posture? It is important to accurately convey this kind of information so that your eyes can be properly tested.
【 2 】 Unnecessarily strong additional power may give you a sensation of swaying or blurring and may result in a narrow field of vision. For this reason, you would be wise not to fall into the trap of believing that starting out with a pair of spectacles with stronger additional power than necessary will mean that you will be able to use your spectacles longer.
【 3 】 To ensure natural vision, it is advisable that the distance between the lenses and your eyes be short. Therefore, it is recommended that persons over the age of 50 in particular intending to use progressive spectacles select a "back-surface progressive lens design," a type that makes use of hybrid technology with the variations in strength on the back surface.
【 4 】 It is very important that you select the frames of your choice after settling on the lens type that will ensure proper vision.
The lens you have selected may not fit the frames depending on the top-to-bottom frame height.
Naturally, the frame design is a matter of concern, but let's be sure to select the frames only after settling on the lens type.
【 5 】 Since the downward rotary power of our eyes (ability to look down) deteriorates with increasing age, a short progressive corridor length (the mid-segment of the lens where the strength is progressively varied) is preferable.
That having been said, types with short progressive corridor lengths feature radical changes in power within a narrow field and may, therefore, be difficult to become accustomed to.
It is important to make your choice after fully discussing these issues.
【 6 】 As far as selecting the store where you wish to purchase your spectacles, it is advisable to choose a store where assistants well-versed in eye tests will understand the above points and give you reliable advice to help you make your choice.
【 7 】 You will often see offers of sets that comprise of lenses and frames for a fixed price, and, for spectacles with low additional power, you may wish to make price a determining factor in making your choice.
However, people over the age of 50 purchasing a pair of progressive spectacles for the first time with an additional power of 2.00 D or higher would be well advised to select lenses (e.g. back-surface progressive lenses) that will minimize any sense of swaying or blurring.
So, if you are the kind of person who has so far resisted the idea of wearing spectacles for correction of presbyopia, or who would like to give such spectacles a try, but are hesitant because you are unsure of when you should start using such spectacles, or what kind of lens you should choose, has the above information been useful?
We all feel a sense of resistance when we hear the word "presbyopia," but remember that your eyes are a part of your body that you want to preserve in as good a condition as possible for the rest of your life.
To preserve our vision and maintain the health of our eyes in the long term, let's use accurate knowledge of lens types to ensure ideal vision for ourselves throughout our lives!!