Gerry Lynch asked:
At my last eye examination the optician said that I did not need to use glasses for driving but glasses could improve my vision. When I started to use them I noticed my eyesight improved for driving but if I forgot to put them on I also noticed my vision without glasses had significantly deteriorated. Is this the other side of visual acuity training? i.e. do your eyes become lazy when you wear glasses?
Hannah - Great question Gerry, and it's one that many people ask. So, quite a lot of eye conditions are diagnosed in the teenage years, so you'll see a lot of teenagers starting to wear glasses in their early adolescence. Then they might find that their presciption changes and that their eyesight is actually decreasing, and they might be thinking "well hang on a second, are the glasses actually making my eyesight worse?"
What seems to be the case, actually, is that their eyes are still developing and the way that they focus light onto the retina at the back of the eye, which helps to make sure that they can see things in a clear way, so it's not blurry for either short sightedness or long sightedness. That lense is still developing and still changing in the eye all the way through to about the mid-twenties along with the rest of the brain. So the teenagers aren't seeing that the glasses are actually changing their prescription, it's that their eyes are actually changing and therefore that's why their prescription might be worse.
Chris - It’s a very good question because a lot of people say, “I started wearing glasses and then my eyesight got a lot worse.” I'm wearing glasses. Ramsey is wearing glasses. Is that your experience?
Ramsey - Yeah.I think part of it might be again, this kind of relative behaviour that we have that your eyes start getting used to the fact that they don't have to work as hard when you've got lenses on. But I suppose it’s very hard to tell because if you're going through the process of losing your eyesight then after a year and you take your glasses off, you go “My eyesight is even worse than it was a year ago.”
Chris - Yeah, because that was going to be my point that when I was growing up, obviously, along with many people, I started wearing glasses in my teenage years. Was that your experience, Helen as well?
Helen - Yes, I was doing my A levels. I remember I couldn’t read the clock when I was looking up from doing work. I think that was another thing is, reading and looking at close screens. Does that make your eyesight worse? And I've been told no, if it’s going to get bad, it’s going to get bad, and maybe get you get bad quicker, but it would’ve happened anyway.
Chris - Exactly. If at that time in your life, the same processes of development which are making you become short-sighted for example, are still going on, when you put the glasses on, obviously, you see better. But then the process is still continuing along underneath that, so your vision continues to deteriorate and then you think, “Oh! I got these glasses. It was alright, but now look, it seems to be getting worse.” Actually, it’s the same deterioration you were going to get. Once people get a little bit older then their vision settles down and they stop getting the deterioration. My lens prescription changed when I was teenager but then it stopped changing and it’s been the same for many years ever since. Tamela...
Tamela - Well, I have a question for you maybe. So, I have been very short-sighted since I was about 11. I had to get glasses and I thought maybe it was because I was reading a lot as a child, but I have two younger sisters and they both about the same age needed glasses and my mother as well. I was wondering if it’s genetic. Do we know this?
Chris - There is an element of that. People have found this runs in families, but the really interesting thing is, if you look at populations in Singapore and you look at individuals in China, the Chinese now are putting on their desks at school, bars so the kids can't get their heads close to their work because we know there's an association between a lot of close work and not developing distance vision in young kids. Singapore has a really big problem with their military. They were struggling to recruit people who had good vision. So, it might be there is a genetic effect and that genetic effect manifests when you give it the chance to. In other words, if you are genetically predisposed to get short sight and then you do a lot of close work, and you don't force your eyes to develop a longer capacity, you might then become short-sighted. So, I don't think it’s as simple as saying, “My dad is short-sighted. Therefore, I will be.” It might be sort of loading the dice a little tiny bit.