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If you have difficulty seeing both long and short distances, then you might want to consider getting yourself a pair of bifocals. Bifocal lenses are divided into two separate parts to accommodate a combination of any two different prescriptions into one lens. One area will usually have one distance prescription, and the segment in the lower half will usually be a near vision prescription.
A bifocal lens allows for clear vision for both long-distance and close up work within one pair of spectacles. Think of them as the same as your ordinary single prescription lenses but with an additional reading segment located towards the lower half of the lens.
Bifocals may have been suggested to you if you have both myopia (short-sightedness) and presbyopia (long-sightedness). Typically worn by people over the age of 40-45 who need support due to the effects of presbyopia, a condition where the lens inside the eye naturally loses its ability to focus on nearby objects.
Presbyopia is a perfectly normal part of the ageing process. Most people become aware of the condition when they start holding phones or books further away from the face in order to see clearly. If you are over the age of 40 and these effects sound familiar to you, I would suggest going to visit your local optician for an eye test.
If you weren't already using distance vision glasses and your optician diagnosed you with presbyopia, then you will likely be prescribed a pair of single vision lenses. However, if you already have issues with short-sightedness, then bifocal lenses may be one of the options available to you.
1. One pair of glasses for everything
The main draw of bifocals is that they are multifunctional and prevent you from having to switch between two different pairs of glasses to perform various tasks. Look straight ahead for normal distance viewing and downwards when reading or doing other close-up tasks.
This prevents you from having to buy a separate pair of reading glasses and have to constantly carry them around. The biggest advantage of bifocal lenses is convenience.
2. Cheaper than other options such as progressive lenses
If you have been diagnosed with both short-sightedness and long-sightedness then you may have heard the term progressive lenses used. Progressive lenses are a more advanced version of the bifocal or trifocal lens with a less drastic difference in prescription types.
There are a few reasons why you might pick bifocals over the much more modern progressive lenses. The first reason is that bifocals are considerably cheaper. So, if your wallet is feeling a bit light, but you don’t want to be carrying around an extra set of glasses everywhere, then bifocals are an excellent option.
3. Easier to adjust to than progressive lenses
The second reason you may want to opt for bifocals over progressive lenses is that progressive lenses have a long adjustment period. When trying any multi-focal lens for the first time, there is a period in which you have to train your eyes to look through the correct areas of the lens, depending on your current task.
This adjustment period is much shorter when using bifocal lenses as they are much easier to use and more accessible. When using other multifocal lenses, you may struggle with dizziness, headaches and nausea for the first few weeks of using them since you will be looking through the wrong prescription of lens. You will have much fewer of these issues when using bifocals since they are easier to adjust to.
1. Distracting bifocal line
Many people find the drastic difference between the two prescription types distracting and irritating. With such a stark distance in lens types, the line between the two prescriptions or the bifocal line can obscure your view. By using two different lens types, you are effectively cutting your line of sight in half and reducing your field of view.
2. Potential visual distortions
You are less likely to experience visual distortions when using bifocals than with other forms of multi-focal lenses; however, this doesn’t mean you will have no issues with disrupted vision. These issues become less common as you get used to the glasses, so luckily, this is only a temporary issue.
One common issue experienced by people who wear bifocal glasses is having difficultly climbing stairs. When you look down, you are looking through the section of the glasses intended for reading. As a result, your feet may look bigger, and it may feel as though you are higher above the ground. This means you may have difficulty gauging your step when climbing stairs or stepping up a curb.
3. It takes some time to adjust
It is much easier to adjust to bifocals as opposed to other types of multifocal lenses; however, you may still have difficulty if you are only used to single lens glasses. In the adjustment period, you have to train your eyes to look through the correct section of the glasses at the proper time, so if you are looking through the wrong prescription lens, you may have issues with headaches and nausea.
Find more about this topic:
What are advantages and disadvantages of progressive lenses
What are the advantages and disadvantages of bifocal lenses
What is the difference between single vision and progressive lenses
Transition lenses problems you should know
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