Norman Swan: Stroke is one of the most feared medical conditions after cancer, and while most of us think of paralysis and being unable to speak, one really disabling consequence of a brain attack is loss of vision to one side or the other. It's called hemianopia.

Alex Leff is a neurologist at University College London and Queen's Square Hospital and has developed two online therapies for such people.

Alex Leff: The patients have all got acquired disorders of vision, usually due to a stroke but it could be due to head injury or brain tumour, but stroke is the commonest.

Norman Swan: And how common is it in stroke, because I think there has been an Australian study, hasn't there?

Alex Leff: Absolutely right, the best study of the prevalence was an Australian study which showed that over the age of 50 about 0.8% of adults have got this visual problem which is called a hemianopia.

Norman Swan: So they don't see out of half of their vision.

Alex Leff: That's right. Now, 0.8% might not sound like a lot but that means for every million people in the population you've got 8,000 who have got this problem.

Norman Swan: So a stroke or a brain injury and it's just a damaged part of the visual nerves that go to the back of the brain to translate visual information to electricity.

Alex Leff: Everything is sort of flipped around in the brain, so in terms of vision it seems a bit odd because your eyes are at the front but the visual bit of the brain is at the back of the brain. The left side of the brain at the back looks after the right-hand side of the world, and the right-hand side of the brain looks after the left-hand side of the world. So if you had a stroke or injury to the left occipital lobe which is at the back of the brain, then there's a good chance that you'll have what's called a right-sided homonymous hemianopia, and that means that when you are looking straight ahead pretty much everything to the right of where you were looking will be invisible, you won't be able to see it.

Norman Swan: And it's not a problem of one eye, this is a problem of both your eyes because it's a problem in your brain rather than in one eye or the other.

Alex Leff: A lot of people not unsurprisingly think they've got an eye problem and will often go to an eye hospital, but if you've got a problem in both eyes it's almost certainly a brain problem, not an eye problem, and the commonest cause in an adult would be a stroke, so you need to go to a hospital and be treated as an emergency for potential stroke, not go to an eye hospital and think there's something wrong with your vision.

Norman Swan: Not everybody who's got hemianopia knows they've got it.

Alex Leff: Probably the commonest cause of a transient visual loss, a bit like a hemianopia, is migraine. A certain group of people with migraine will get what's called an aura. Usually though the vision, instead of disappearing you get sparkly lights or zigzag lines in the vision and that will sort of march across the vision a bit like a cloud and then disappear, lasting for 20 minutes or so. But with a stroke you lose all the vision there. But perhaps not surprising when people just have the loss of their vision they think maybe it will pass, maybe it will clear. Strokes are very rarely painful, so people will often just wait and see if it passes, and unfortunately that's not a great idea because the treatments that we've got now for acute stroke really need to be given in the first few hours after a stroke. A lot of patients I see, their vision will be a bit funny and they will go to bed and sleep on it and then it's still there the next day and then they go and get help.

Norman Swan: And this can be the primary symptom of your stroke rather than weakness in your arm or leg or failure to speak.

Alex Leff: Absolutely. There's been a big public health campaign in the UK to try and raise public awareness of stroke. The commonest symptom after a stroke is exactly as you say, weakness down one side, usually the arm and the leg or face and the arm, and the second commonest symptom is a problem with speech. But probably the third commonest symptom is a problem with vision and that hasn't made it onto the radar, in this country anyway.

Norman Swan: And you've been looking at ways of treating this.

Alex Leff: Many of the functions of the brain which are damaged by stroke will improve with time. Unfortunately with vision, the visual bit of the brain is fairly hardwired in the first few months after birth, and if you lose the bit of the brain that deals with vision it's really not possible for other bits of the brain to take over.

Norman Swan: There's not much plasticity.

Alex Leff: Absolutely. However, that's not the end of the story. You can still get around the problem. We all move our eyes when we see, vision is an active process. You might think of vision as being a passive process where information just flows into the eyes and then into the brain, but it's actually a very active process and we are moving our eyes all the time, roughly about three times a second you are moving your eyes, and what you are really doing there is sampling the world and sort of making up a picture that you hold in your mind. And the idea that you can see everything in front of you at the same time isn't in fact the case but that's what your brain makes you think is what's happening.

Norman Swan: Because your brain is pretty good at filling in the gaps.

Alex Leff: The brain is very good at filling in the gaps. So when you are actually looking at the world you've only got what's called high acuity vision, very good vision, actually for just a tiny little bit of vision in the middle of your vision. But by moving your eyes around a lot, as I say, you are kind of continually painting a picture of what's going on. And there are all sorts of interesting experiments where if you distract someone's attention you can change large portions of the visual scene and they won't notice. This is normal people.

So when you've had a stroke and you are missing half your vision you can still use that same machinery, in other words the eye movement parts of the brain, to in some way compensate. In other words, if you can move your eyes more efficiently around the scene in front of you, although you won't go back to normal, your behaviour will improve. In other words, you will think that your vision has improved.

Norman Swan: How are you doing that?

Alex Leff: You really just have to practice certain types of exercise that improves certain types of eye movement. And recent evidence suggests that the task that you practice on is the one that you improve on. So you can't just practice any old eye movement, but if you practice a specific eye movement, for instance for reading, you should improve your reading speed by around 40% or maybe more, which won't bring you back up to normal. But if your main problem is not with reading but with finding objects around you, then you need a different sort of eye movement practice.

Norman Swan: Getting specific training, it's rather than just going for a jog, if you're going to play soccer or football you do football training to learn how to do it.

Alex Leff: Absolutely, it's a bit like squash and tennis, you know, if you practice at squash you are probably not going to get better at tennis and vice versa.

Norman Swan: And you are doing this online?

Alex Leff: That's right. Although the condition is relatively common, patients with it tend not to go through the classical patient pathways. Not everybody realises they've had a stroke, and if you miss out early on on the stroke pathway you don't get fed into it. Also if you've just got a problem with your vision you tend not to end up in a rehabilitation unit, you tend to not end up necessarily being part of stroke groups and things like this. So the vision can improve spontaneously and it often does over the first few weeks and months, but it's usually stuck by about three or six months. But as I've said, that doesn't mean there is nothing that can be done. You can practice these programs.

In an initial study that I did on this many years ago, which was on one of the two websites I've got going now, and this one was specifically for reading, we showed that if you practice these reading eye movement exercises you get quicker at text reading, and then we published that result and that was all fine, and we did that by bringing patients in to our unit, studying their eye movements, collecting quite a lot of scientific data on them. And of course they had to practice the material, and the way that we gave them the material (and this shows how long ago this study was) we put it on little VCR tapes. They were Sherlock Holmes stories because they were out of copyright. And whenever they got bored with it or wanted a faster one or more material they would have to post the VCR back to us and we would post them a new one.

Once we published that I was keen that we made this available to people. Initially I was thinking of putting it on DVDs which actually would have been a bad idea because they look like they are on their way out now too. But I spoke to UCL multimedia department and they suggested what of course was a great idea which is put it on the web. So once we found a way of animating the text across the web of course that's the way to do it because people can control what they are reading, they can control the speed, the colours, and most importantly they control when they get the practice in. So generally speaking what's important is getting in enough practice, but you have to do it when it suits you.

Norman Swan: So show me the program and how you get trained. So you are sitting in your office looking at your computer screen…

Alex Leff: Yes, so the one called Read-Right is a web program for patients with this condition called hemianopic alexia, and generally speaking is when the hemianopia is to the right-hand side.

Norman Swan: And 'alexia' meaning you have trouble reading.

Alex Leff: Exactly. The therapy is very simple, you just have to read text that is scrolling, so-called Times Square text, you'll see it sometimes on advertising hoardings or tickertaping across below the news or sometimes at bus shelters.

Norman Swan: So we're watching words in blue letters going from left to right across the screen and it's telling a story. Are the colours significant?

Alex Leff: No, the colours aren't significant. People who use the website can change the colours, they've got absolute control over the colours, they can make it as a garish as they like.

Norman Swan: So what's happening to my eyes as I watch, as I read these words going across the screen?

Alex Leff: I'd probably have to speed it up a little bit but what it is inducing is…

Norman Swan: It's inducing vertigo at the moment!

Alex Leff: Yes, actually this one that is on is streaming live over the internet, and technically that was the big problem that we had was getting it to go smoothly. So the only way to get it go really smoothly is to have it as a downloadable app so it runs off your own computer so the text doesn't actually stream live over the web. But the one that we're looking at is doing that. What it's doing is inducing a specific type of eye movement which has got a technical name called optokinetic nystagmus…

Norman Swan: Where your eyes move to the left and then flick to the right quickly…

Alex Leff: Absolutely, so it's the motion of the words that is causing the eyes to be dragged along with the words and then you get this reflexive saccade which is a ballistic movement of the eyes back towards the right, and that really is the therapy, it's that eye movement over to the right.

People would have seen this eye movement, if you watch…you have to be careful how you do it, but if you watch people across you in the train or something like that, as the train pulls out of the station people will get this eye movement induced and you will see their eyes flickering back and forwards. So it's a very common thing, everybody gets it, and you don't really feel it because you can't feel your eyes moving, but we are basically making use of this eye movement to provide therapy.

Now, it could be anything moving across that screen, it could be dots, it could be anything, but of course no one is going to sit there for hours of therapy watching dots. So we've put words on there because that gives people something to do while they are getting the eye movement induced, if you like, and also it is a reading thing, so it makes them feel like it is actually what they are hopefully trying to work on.

Norman Swan: So we are reading Alice in Wonderland at the moment.

Alex Leff: Yes. So on the demonstration on the website we've only got some limited materials, but for people who log in there's quite a wide range of books. We again tended to pick things that were out of copyright, so there's a rather old-fashioned feel to some of the books that are on there. But we also did write to some authors currently and we got Harry Potter on, so that was very nice, JK Rowling gave us permission to put some of her books on.

But the real thing that has made it very useful is that the BBC gave us permission to use their RSS feeds which are effectively the free text that you can find on a lot of websites. And of course on the BBC website text is continually changing from news stories or sport or entertainment, and if people click on that then that text just gets fed into our reader.

Norman Swan: So while you are training you are getting the news.

Alex Leff: If you want you can get the news or the sport or the entertainment, whatever is on that website.

Norman Swan: So how much training, how often, for how long?

Alex Leff: That again is really up to the individual. We suggest about 20 minutes a day. The evidence from not just our study but other people's studies suggests that you need about seven hours of therapy. That doesn't mean seven continuous hours, you'd go a bit cross-eyed if you did that, but you just need to build up those hours of therapy over a few weeks, or some people even take a few months to build it up. But on average when people practice for seven hours or more they improve by 20% to 40%, their reading speed. But it seems the more you practice the more you speed up as well, so we've got some evidence for that.

Norman Swan: So you can go beyond the seven hours.

Alex Leff: Absolutely, so we recently published a paper in the Journal of Neurology showing that if patients went up to about 20 hours of therapy in total they would improve by about 40%.

Norman Swan: And you've got another one as well, another online therapy program too.

Alex Leff: The Read-Right one is generally speaking for people who've got a right-sided hemianopia because the problem is with English text, when you've got a hemianopia to the right you can't see the words coming up, whereas when you've got a hemianopia to the left it's less disabling in terms of reading, your main problem is finding the next line, and most people get around that. So you've got to have a right-sided hemianopia, generally speaking, to benefit from Read-Right, although both types of patients can try, and also some people…not everyone cares about their reading as much as you might think, or maybe their spouse will read for them or they weren't great readers.

The other website we've got is also for patients with a hemianopia. Almost everybody with a hemianopia has trouble with what we call visual search, that means in a busy environment, which most environments are, say finding things in front of you on a crowded desktop or on the table in front of you when you are looking for your glass or the salt or the pepper, patients with hemianopia they can usually find those objects but they are slow to do so. And the new site that we've just released called Eye-Search uses a different type of eye movement therapy to improve visual search, and there's a whole bunch of tests on that website, it's a bit more sophisticated.

Norman Swan: Let's have a look.

Alex Leff: Yes. On this website there's the therapy itself, but before people get onto the therapy they have to take four tests which are baseline tests, these are important because after they have racked up a certain number of trials on the therapy they come back and do all the baseline tests again, and then they can look up their results. So in other words you can see how it's actually working for you and whether it's working for you or not and whether you should continue or not.

The actual therapy itself, a bit like with the Read-Right one, you just have to rack up a large number of trials, and we are talking here hundreds of trials, in some cases thousands. So we've tried to make it into a little game. Basically there's a little ball that rolls across the screen and then in a slightly unpredictable way it jumps at a certain point and you then have to find it.

Norman Swan: So simply forcing your eye to track.

Alex Leff: Absolutely. While you're busy doing the treatment you are having to use a variety of eye movements in order to do it, even though you are not particularly aware of that, and it's those eye movements, it's that jumping eye movement to one side or the other that we think is the therapeutic eye movement.

Norman Swan: And these sites are accessible from Australia?

Alex Leff: Obviously it is a UK-based website but the whole point is that people anywhere in the world can use it. And after the UK, America comes next, but then Australia in terms of people accessing it.

Norman Swan: Alex Leff is a neurologist at University College London and Queens Square Hospital.