Whether you should choose reading glasses, bifocals or varifocals depends on a variety of factors.
First of all, reading glasses will be your prescription for close work only. If you look up into the distance through them then everything will be blurred to some degree, depending on how strong your reading prescription is. In terms of the lens, the whole lens is clear for reading, there is no line on the lens and no distortion/soft focus at the edges.
Bifocals are a lens which has your distance prescription at the top (or clear if you don't need distance glasses) and then a segment at the bottom of the lens to see close up. This is either a line across, a D shape, a C shape or a round segment. The round segment is less visible to people looking at you where as a line all the way across will be most obvious. There is no intermediate area of vision and no soft focus at the edge.
Varifocals are a blended lens starting from your distance prescription at the top getting gradually stronger to give your reading prescription at the bottom of the lens. This means you get an intermediate area that is useful for focusing on computers, reading music etc. The downside is there is some soft focus at the edge of the lens. Most people will tolerate a varifocal well but or those who don't, most opticians will have a guarantee where you can bring them back and switch to a bifocal or separate pairs.
So to decide which is best for you, read on!
Option 1: You already wear glasses for the distance.
If you are shortsighted then more than likely when you start to struggle for reading then you can just take your glasses off/lift them up to see the small print. When it gets to the point that you're lifting them up and putting them back on all day long then you'll probably decide that a bifocal or varifocal is easier. If you are someone who does a lot of computer work and close work and needs to see in the distance too then a varifocal will probably be easier from the start so that you can just wear one pair of glasses and see at all distances. If you can start getting used to wearing a varifocal from when you have a low reading prescription then it will be easier to adapt to that when you have a higher reading prescription. If you don't do any close work and have no intermediate demands (eg reading music, talking to people face to face) then a bifocal is still a good option.
If you are long-sighted then as you age you can't take your glasses off to read so if you don't choose a bifocal or varifocal straight away then you will need a separate reading pair for close up. This means you will have to swap between your normal glasses and your reading glasses as needed. The advantage of separate pairs is that the whole lens is for whichever task you are doing, there is no distortion at the edges like in a varifocal. The obvious disadvantage is that you have to swap your glasses every time you need to see to read. When you are only just starting to need reading glasses this might be ok as you'll only need to use them for small print. Of course, you can use a bifocal or a varifocal as soon as you start to need reading glasses which solves the problem of swapping pairs.
Option 2: Normally you don't wear glasses and you've been told you need reading glasses.
If you've never worn glasses before and you start to struggle with reading (between age 40-50 usually) then to go from not having to use glasses to wearing a varifocal all the time can be quite daunting. This is why a lot of people just choose to have a pair of reading glasses so they can just put them on if they're struggling to see something and carry on without glasses the rest of the time. As we age we start to struggle more for reading even larger print, seeing food, sewing etc then just using reading glasses will mean that they are on and off a lot and this can be quite irritating. For example, you pick up your phone but wait, where are your reading glasses? You find them, put them on then someone shouts you from across the street, you look up to see who it is but they are all blurred because you have your reading glasses on so you take them off etc etc. At this point many people will choose a pair of bifocals or varifocals so that there is a clear part with their distance prescription at the top so they can see when they are walking around/driving/watching tv etc as well as looking down to read and eat their food etc. Some people will prefer to wear them all the time or some people will still put them on and off as needed but the advantage is when they are on, they can see everything.
Option 3: You are a plumber or a mechanic.
If you have a job that requires you to see close up when you're looking up or straight ahead, then a varifocal or a bifocal will he no use as the reading area is at the bottom of the lens. So in these cases a single vision pair of reading glasses will be better as the reading prescription will be over the whole lens so no matter which direction you look, you will have the right correction for the close work you are doing. There is an option of having a bifocal with a reading segment at the top too.
Option 4: You aren't very stable on your feet.
Often elderly people who are unable to walk very well may not be suited to a varifocal or a bifocal because of the magnified area at the bottom if the lens. This can make the ground look magnified and be difficult to cope with if you are already unsteady on your feet. In these cases it might be better to just have a separate pair of reading glasses to use when they are sitting down safely. If these patients are already used to walking in a varifocal or bifocal and have done for years then there is unlikely to be a problem so if they want to carry on using their bifocals/varifocals then they can, just be aware of any change in mobility.
Generally it is personal choice whether you want to wear glasses all the time or just as and when you need to. Hopefully this blog has helped you make a more informed decision.