What is long sight?

Long-sighted?

When you're long-sighted, you are technically hypermetropic. You are a hypermetrope. That's the technical term for it. Now what long-sightedness actually means is, it's a little bit harder to understand than short-sightedness, because when you are short-sighted, you just can't focus the distance and clear it, whereas long-sighted people, depending on the power of your prescription and how old you are, you can quite often focus to get the distance clear. We say long-sighted people can see in the long distance, but not up close, so hence the term long-sighted. You are sighted a long way away from you. And that is because long-sighted people, your lens, well everyone's lens can change the shape to focus light to see further away, you can focus through that long-sightedness.

So what a lot of children who are long-sighted do, again depending on the prescription, (if there's a lot of long-sightedness there, it can cause its own problems). But if your child is moderately long-sighted, they may never, and you may never realize they are longsighted because they are focusing through that. They've got enough focus to focus through the long sight and keep everything clear. So this is why when someone's long-sighted, essentially what they're doing is over-focusing in the distance constantly to clear it. So they're using their focus mechanism to clear up the distance when naturally we shouldn't need to use that focus. When you're long-sighted, we can think of the eye as being a little bit it too short, perhaps, or the front of the eye is a bit flat. It's not curved enough, so therefore when it bends the light, it's focusing the light almost behind the retina. It's not falling to a nice, neat focus on the retina. So therefore, if the eye's too short, it's focusing behind the retina.

Now the handy thing of about being long-sighted, as I said, is, your little lens in your eye can change its shape to fatten and help to bend the light. So if the light is being focused behind the retina, the lens can change its shape and try and pull that focus forwards onto the retina. Now you can't do that in short-sightedness, it's the opposite way around. So hence long-sighted people will overfocus the distance all the time. So they usually have quite clear distance vision as long as they've got enough focus to keep it up.

The problem that comes for long-sighted people is seeing up close, because if you're constantly over focusing in the distance, you're already using up your focusing to see the distance. So to naturally see up close you may not have enough focus left over, which will cause you problems. So long-sighted people are going to have more problems with reading vision than they are with distance vision quite often, because of that natural use of the focus in the distance and you've not got enough left. It doesn't always necessarily mean you're going to get blurred reading vision, but quite often long-sighted people will get eye strain, which is usually a dull headache across the eyes that'll come on as the day progresses, or they'll have spells of eye strain or spells when they'll constantly frown at things up close, like frowning and furrowing the brow and kind of squinting and just generally uncomfortable to read after a while. So that's why people need glasses for long-sightedness. It helps to relax the distance focus and you can then use your natural focus to see up close.

For glasses do to correct it, you need a positive or plus lens, so that the light hitting the front of your eye is coming in at you. It's converging into you so that your flatter cornea can naturally move that back out, so we're stretching where the focal point goes. So the focal point will be pulled forwards and focus onto the retina. Now these lenses are thicker in the middle and thinner at the edge. Again, depending on prescription, you may need to look at a flatter and thinner lens. We have some pretty amazing lens technology available to us now. We have what's called aspheric lenses, which flatten the lens out so it's not as curved and curved and bulbous. We also have bi-aspherics, which are amazing, which improve even further. And again, you might need a thinner lens material so the lens isn't as thick and as heavy.

So just to recap, long-sighted people tend to overfocus the distance, so the distance is clear. Because you've used up focusing in the distance, it's harder to read, so the reading could be blurred or you could be getting a lot of eye strain and things like that. Again, the modern day use of computers, we do get a lot of people with just very small prescriptions for long-sightedness, needing them because they're on a computer. Now it's not the computer causing damage to the eye to make them need glasses. It's the fact that with what they're doing all day, every day, their eyes are becoming strained because of that long-sightedness being there.

If you had this prescription but you worked in a field all day and you weren't on a computer screen, you wouldn't need the glasses because you're not doing the thing that's going to cause the eye strain. If your job were a country park ranger and you were out walking in the woods all day, you're not going to need the glasses because you're not going to get the eye strain. But if your job was to proofread books and you were sat with papers all day, you're going to get eye strain, because you're doing the stuff that's the hardest for your eye to do, that close stuff. That’s why it can be hard for people to understand what longsightedness is as some people need to glasses to help, whereas others don’t.